~GEMSTONES & MINERALS~
ABALONE
Abalone is a mollusk whose shell is iridescent on the inside; abalone is a source of mother of pearl,which is used in jewellery making.
ACROITE
Acroite is a rare, colourless variety of tourmaline.
ADULARIA
Adularia is a common type of moonstone, a whitish-bluish semi-translucent stone. Adularia is usually set as a cabochon. Adularia was very popular early in the 20th century and was extensively used in Art Nouveau jewellery. Adularia has a hardness of 6 and a specific gravity of 2.57.
AFRICAN EMERALD
African emerald is a misnomer for green fluorspar that is mined in South Africa; it is not an emerald at all.
AFRICAN JADE
African jade {also called Transvaal jade} is a misnomer for massive green grossular garnet that is mined in South Africa; it is not jade, but does look like jade. It can be light green, white, or pink.
AGATE
Agate is a variety of chalcedony {a family of microcrystalline quartz }. Agate is a very common stone that is often used in jewellery. It is found in a wide range of colours, including black, gray, brown, reddish, green, pink, blue, and yellow. Agate can be flecked with colour and is often banded, exhibiting layers of quartz. Agate is porous and takes dye easily; it is frequently dyed to enhance the colouration and the banding. White agate was used often in Victorian jewellery, mostly as a background. Moss agate has green, red or black dendritic inclusions.Onyx is agate whose bands are parallel. Eye agate has banding arranged in concentric circles. Agate has a hardness of 6.5 to 7 and a specific gravity of 2.6.
ALEXANDRITE
Alexandrite is a mineral {a type of chrysoberyl} that appears to be different colours depending on whether it is viewed in natural or artificial light. Alexandrite appears to be red when seen in candle light and blue to green when seen in fluorescent light. Alexandrite was discovered on the birthday of the Russian Czar Alexander II, and it was named in his honor. Alexandrite is mined in Russia, Brazil, Burma, Ceylon, and Rhodesia. Laboratory-produced alexandrite is common, and it is often sold as natural alexandrite. Alexandrite has a hardness of 8.5 and a specific gravity of 3.64-3.74.
ALMANDINE
Almandine is a type of violet-tinged variety of garnet that ranges in colour from deep red to reddish-brown. Almandine is the most common kind of garnet. Star garnets are almandines that exhibit an asterism. Almandine has a hardness of 7.5 and a specific gravity of 3.85-4.20.
AMAZONITE
Amazonite is an iridescent stone that ranges in colour from green to blue-green. Its composition is potassium aluminosilicate {KAlSi3O8}, and is a type of feldspar {a green variety of microcline}. Amazonite is usually set as a cabochon {since it breaks easily if faceted}. This mineral was named for the Amazon River, where it was first thought to be found in the middle 1800s {the mineral found in the Amazon was actually a form of jadeite}. Amazonite is also found in the Ural Mountains of Russia, in Colorado and Virginia, USA, Russia, Australia, and Africa. Amazonite has a hardness of 6 and a specific gravity of 2.56-2.58. Most Amazonite is opaque, but rare crystals are transparent.
AMBER
Amber is translucent fossilized tree resin {from conifers}, a natural hydrocarbon that comes in many colours, including yellow, reddish, whitish, black, and blue. Amber is flammable. Rubbing amber produces static electricity. The word electricity comes from the Greek word for amber, "elektron." It used to be thought that amber possessed magical powers that protected the wearer from evil. Pressed amber consists of small pieces of amber that have been fused together to form a larger piece. Fake amber is easily made from plastics, and buyers must beware of cheap imitations sold as natural amber. Amber has a hardness of 2.5 and a specific gravity of 1.05-1.10.
AMERICAN RUBY
The term "American ruby" is actually a pyrope garnet {and not a ruby at all}. There are real rubies found in the US, but they are not referred to as "American rubies."
AMETHYST
Amethyst {Greek for "not drunken"} is a form of the mineral quartz, and is a relatively common gemstone. Amethyst is usually purple, but can range in colour from pale lavender to a very deep, reddish purple to a milky colour to green. Deeper-colored amethysts are more highly valued. The ancient Greeks believed that amethyst made one immune to the effects of alcohol. Synthetic amethysts are hard to distinguish from the real stone.
AMETRINE
Ametrine is a variety of quartz a mixture of amethyst and citrine. Ametrine is partially purple and partially orange-yellow.
AMMOLITE
Ammolite {also known as korite, calcentine, or Buffalo Stone.} is a fossilized, opalized ammonite shell used as a gemstone {it is the shell of the ammonite, a fossilized marine animal, a cephalopod } It is a gray, iridescent stone with flashes of green, red, yellow, blue or purple {blues and purples are rare}; the colour changes as the stone is turned. Ammolite has a hardness of about 4 {it is very brittle before it is treated} and a specific gravity of 2.8. Ammolite is usually treated with a colourless, hard material to increase the strength of the stone and is often mounted as a doublet or a triplet {with a quartz top layer and a shale underside}. Ammolite is only found in southern Alberta, Canada.
ANGELITE
Angelite {CaSO4}; it is a pale blue variety of calicium sulfate = anhydrate {it is gypsum that has lost water and crystallized}. The stone is quite brittle; crystals are transparent to transluscent. Angelite stone has a hardness of 3 to 3.5 {quite soft} and a specific gravity of 2.9 - 3.0.
ANGELSKIN CORAL
Angelskin coral is a pale pink coral, from deep sea coral. Angelskin coral is one of the most valued colours of coral {red is also highly prized}. Coral is an animal that grows in colonies in the ocean.Coral polyps secrete a strong calcium structure that is used in jewellery making. Coral ranges in colour from pale pink {called angelskin coral} to orange to red to white. In jewellery making, coral is either carved into beads,cameos, or other forms, or is left in its natural branch-like form and just polished. It used to be thought that coral protected the wearer, so it was a traditional gift to children. Coral has a hardness of about 3.5 and a specific gravity of 2.6 to 2.7. Since it is composed of calcium carbonate, coral will effervesce if touched with acid. Imitation coral is made from glass, porcelain, or plastic.
APACHE TEARS
Apache tears {a type of obsidian } is a volcanic glass that is usually black, but is occasionally red, brown, gray, green {rare}, dark with "snowflakes," or even clear. This glassy, lustrous form of obsidian is found in lava flows in the southwest USA. Obsidian is formed when viscous lava {from volcanos} cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35.
APATITE
Apatite {calcium phosphate} is a clear to opaque stone that comes in many colours, including green, yellow, blue, violet, and yellow-green {called asparagus stone}. Some apatite stones show a cat's eye asterism. This stone is rarely used in jewellery because it is brittle and soft. Apatite comes from the Greek word for "deceit," because it was easily confused with other minerals. Apatite has a hardness of 5 and a specific gravity of 3.15-3.22.
AQUAMARINE
Aquamarine is a transparent, light blue or sea-green stone that is porous. Today, blue aquamarines are more highly valued, but this was not true in the past, when sea-green stones were prized. Heat-treatment turns greenish stones bluer. The best aquamarines come from Brazil. Large aquamarines are relatively common. Aquamarines are usually faceted but when they are cabochon cut, a cat's eye effect or asterism may appear. Aquamarines belong to the beryl family of stones. Aquamarine has a hardness of 7.5-8 and a specific gravity of 2.65-2.85.
ARAGONITE
Aragonite is a mineral that is rarely used for jewellery. It is transparent to translucent and can range in color from honey-colored to pale reds, blues and greens to clear or white. It forms hexagonal crystals, pyramidal crystals, chisel shaped crystals, and other shapes. Aragonite has a hardness of 3.5-4 {relatively soft} and a specific gravity of 2.9 g/cm3.{average}. Its chemical composition is CaCO3 {it is a form of Calcium Carbonate}. Aragonite is named for Aragon, Spain, where it was first found in 1790. Aragonite is also found in many other European, North African, and some North American locations.
ARCTIC OPAL
Arctic opal is a blue-green stone that is a mixture of azuritea and malachite; it is not a type of opal at all. Arctic opal is mined in the Wrangle Mountains and the Chugach Mountains of Alaska, USA {near Anchorage}.
ARIZONA RUBY
An Arizona ruby is actually a pyrope garnet {and not a ruby at all}.
AVENTURINE FELDSPAR
Aventurine feldspar is also called Sunstone {a variety of oligoclase}. This gemstone varies from golden to orange to red-brown, and can be transparent or translucent. Sunstone is metallic-looking due to sparkling red, orange or green crystalline inclusions {these are hematite or goethite crystals}. Sunstone is found in Canada, the USA {in Oregon}, India, Norway, and Russia. This brittle stone has a hardness of 6 and a specific gravity of 2.63 - 2.67. Sunstone is not enhanced.
AVENTURINE
Aventurine quartz is a type of quartz that has sparkling flecks {includions} of mica or iron. This colours of this stone include red-brown, yellow, gray, and green. Aventurine quartz has a hardness of 7 and a specific gravity of 2.64-2.69. This stone is usually cut with a flat or rounded surface to maximize its sparkle. Aventurine quartz is found in India, Russia, and Tanzania.
AXINITE
Axinite is an unusual, lustrous stone that is brown, yellow, blue, green or gray. Violet axinite is rare {and from Tasmania}. It has both transparent and translucent varieties. Axinite is dichroic. Axinite has a hardness of 7 and a specific gravity of 3.3. Axinite is a boro-silicate of aluminum and calcium. It is used only as a mineral specimen and not in jewellery.
AZURITE
Azurite is a beautiful copper-based blue mineral that is often used in jewellery. The colour ranges from very deep blue to pale blue. Azurite has also been used as a dye for paints and luxury fabrics. Azurite is hydrated copper carbonate; its chemical formula is Cu3{CO3}2{OH}2.Malachite {another copper-based mineral} and azurite are often found together. Azurite has a hardness of 3.5 to 4 {relatively soft} and a specific gravity of 3.7 to 3.9. Azurite is found in massive monoclinic crystals in Australia the southwestern USA, France, Mexico, Morocco, Nambia, Zaire, and Europe. Azurite is sometimes coated with a colourless wax or impregnated with plastic in order to enhance the colour and increase the hardness.
BAFFA DIAMOND
Baffa diamond is actually rock crystal and not a real diamond.
BANDED AGATE
Banded agate is a type of agate with distinct layers of color.
BENITOITE
Benitoite is a rare, blue gemstone that is found mostly in the San Benito River in San Benito County, near Coalinga, California {lesser quality benitoite is found in Mont St. Hilaire, Quebec, Canada}. Benito means "blessed" in Spanish. This gemstone is strongy dichroic; although Benitoite is blue when viewed from most directions, it appears colourless when viewed in a single direction {the c-axis}. Some unusual Benitoite is blue, but pink or orange when viewed through the c-axis. Benitoite is BaTiSi3O9 {Barium Titanium Silicate}; no one is sure what element causes the blue colour of benitoite, but it may be iron. Benitoite has a hardness of 6 - 6.5, a specific gravity of 3.68, and a refractive index of 1.757 - 1.804. Benitoite has a very unusual crystalline shape - it is the only known ditrigonal-dipyramidal crystal. Large stones {over 1 or 2 carats} are exceedingly rare. Benitoite was discovered in California in 1907, either by Mr. Hawkins and T. Edwin Sanders or James Marshall Couch {the story is in dispute}. Heat-treated benitoite becomes orange; these stones are more expensive. Benitoite is California's official state gemstone {since 1985}.
BERYL
Beryls are a family of gemstone that include emerald, aquamarine, beryl {green}, red {red beryl}, morganite {pink}, and heliodor {greenish yellow, named for the sun}, and goshenite {colourless}. Beryl has a hardness of 7 - 8, a specific gravity of 2.6 - 2.9, and the chemical formula Be3Al2SiO6. Internal flaws in beryl gems can be hidden by treating the stone with oil {this is often not disclosed to the buyer}.
BLACK MOONSTONE
Black moonstone is a type of labradorite and not true moonstone.
BLACK OPAL
Black opals are a valuable type of precious opals with a dark ground color. They are luminous, iridescent, and frequently have inclusions of many colours {"fire"}. Opal is a mineral composed of silica {and some water} and is a species of quartz. The rainbow-like iridescence is caused by tiny crystals of cristobalite. Many opals have a high water content - they can dry out and crack if they are not cared for well {opals should be stored in damp cotton wool}. Opals have a hardness of 5.5 to 6.5 and a specific gravity of 1.98-2.50. Black opals are found in Australia.
BLACK PEARL
Black pearls {also called Tahitian pearls} are dark-coloured pearls. They are produced by the large, black-lipped pearl oyster Pinctada margaritifera {also called the Tahitian black pearl oyster}, a mollusk found in the tropical Indo-Pacific Ocean. Black pearls come in many colours, including many body shades and overtone tints including gray {light gray to almost black}, peacock green {especially valuable}, aubergine {eggplant}, and deep brown. The colour of the dark nacre is determined by the minerals in the oyster's diet {plankton} and in its environment. Many "black pearls" are dyed or irridiated to enhance or change their colour; it is difficult to tell a natural pearl from a treated pearl. Tahitian pearls are graded on six factors: 1.Shape {round is most valued}, 2.Size {the larger the better}, 3.Surface Quality= {clean is superior to blemished}, 4.Luster {the more high-gloss luster the better}, 5.Nacre Thickness {thicker is better and longer lasting}, and 6.Colour {overtones atop the body colour add value to the pearl. The most sought-after colour is peacock green and darker colours are more valuable. Overtone colours include blue, pink, gold, silver, aubergine, and peacock green).
BLACK STAR DIOPSIDE
(BLACK STAR OF INDIA)
Black star of India is another name for Black Star diopside {CaMgSi2O6}, an opaque black gem with a white, four-rayed star {an asterism }. It has a hardness of 5.5 and a specific gravity of 3.3 - 3.6. These stones are found mostly in India. Stones are generally cut cabochon and are not enhanced.
BLISTER PEARL
A blister pearl {also called a bouton pearl} is a pearl that developed attached to the inside of a mollusl's shell. This type of pearl must be cut off the shell, and is therefore hemispherical. Because of their shape, blister pearls are mostly used for earrings.
BLOODSTONE
Bloodstone {also called heliotrope} is an inexpensive type of chalcedony that is green with red highlights {caused by iron oxide}. Bloodstone is porous and relatively soft.
BLUE DIAMOND
Blue diamonds are rare, fancy diamonds and are quite valuable. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 - 2.419.
BOHEMIAN DIAMOND
A "Bohemian diamond" is not a diamond at all, it is actually a rock crystal.
BOHEMIAN RUBY
A Bohemian ruby is actually a pyrope garnet {and not a ruby at all}
BOTANICAL GEMS
Botanical gems are minerals that form from plants or plant material. Some botanical gems include amber {fossilized tree resin}coconut pearl {a rare, shiny, calcareous, pearl-like mineral that forms inside the coconut, Cocos nucifera}and pearl opal {also called Tabasheer opal, which form in injured bamboo joints}
BRAGANZA
The Braganza is a huge gemstone that may or may not be a diamond. This Portuguese stone is said to weigh 1680 carats {which would make it the largest-known diamond}, but it has not been authenticated - it may actually be a clear topaz.
CAIRNGORM
Cairngorm is a yellow-brown type of smoky quartz that is often used in traditional Celtic jewellery. Cairngorm was once Scottish topaz. The supply of cairngorm is virtually exhausted, so heat-treated Brazilian amethyst is used as a substitute in Scottish jewellery.
CALCITE
Calcite {Calcium Carbonate, CaCO3} is a very common mineral that comes in a wide variety of forms, shapes and colours. The trigonal crystals range from translucent to transparent. Transparent calcite exhibits a double refraction effect {when you look through the crystal, singel items are doubled}. Calcite has a hardness of 3 {most forms}, a specific gravity of about 2.7, a refractiveindex of 1.49 and 1.66, and a white streak.
CALSILICA
Rainbow calsilica is a newly-found, multi-coloured, layered stone composed of calcium and silica. This stone has been recently used for Zuni fetish carvings and in some jewellery {beads and cabochon cut stones}. Rainbow calsilica was only recently found in Mexico or Northern South America {it's origin remains mysterious}. Some people theorize that this stone formed as a result of the runoff of mining or oil-drilling chemicals, and has only formed in the last 30 to 50 years {but this is uncertain}.
CANARY DIAMOND
Canary diamonds are diamomnds that have a deep yellow colour. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 - 2.419.
CAPE AMETHYST
Cape amethyst is a form of amethyst that is layered or striped with milky quartz. Cape amethyst is a translucent gemstone that ranges from light- to medium-purple and has white bands.
CARBONADO
A carbonardo is a rare type of opaque black diamond; they are not used for jewels, but for items like drilling bits and abrasive wheels. They were once thought to have been formed as a result of a comet impact 2 billion years ago, but this is no longer thought to be true. The largest diamond ever found was a carbonardo that weighed over half a kilogram. Carbonadoes are found in Bahia, Brazil, South America. Unlike other diamonds, carbonadoes are not found in a crystallized form - they are found in irregular or rounded fragments. Carbonadoes have a hardness of 10 and a specific gravity {density} of 3.1-3.3. Diamonds have a very hard polycrystalline carbon structure.
CARBUNCLE
A carbuncle is a cabochon-cut garnet.
CARNELIAN
Carnelian {also called cornelian and carneole} is a reddish form of chalcedony {a type of quartz}. This translucent stone has a waxy luster. The best carnelian is from India. Most commercial carnelian is really stained chalcedony. Carnelian has a hardness of 7 and a specific gravity of 2.61.
CAT'S EYE CHRYSOBERYL
Cat's eye {chatoyant chrysoberyl} is a yellow to green-yellow to gray-green stone with a bright, pupil-like slit that seems to move slightly as the stone is moved. Most Cat's eye is cut as cabochons to maximize the distinctive pupil-like effect. Most cat's eye chrysoberyl is found in Brazil. Cat's eye chrysoberyl has a hardness of 8.5. This stone is sometimes enhanced by irradiation {this process improves the color and accentuates the stone's asterism }.
CHALCEDONY
Chalcedony is a family of minerals {microcrystalline quartz} that are often milky to gray to bluish in colour. Chalcedony includes agate,carnelian {waxy red}, chalcedony {blue}, chrysoprase {green}, onyx {black and white}, bloodstone, sard {brownish-red}, jasper {hornstone}, seftonite, and others. Chalcedony is porous and translucent. Chalcedony has a hardness of 6.5-7 and a specific gravity of 2.6.
CHAMPAGNE DIAMOND
A champagne diamond is a pinkish brown diamond {having a colour of C2-C3}. Most champagne diamonds are mined in Western Australia {in the Argyle Mine}. The colour is produced a low nitrogen content.
CHAROITE
Charoite is a very rare, bright purple mineral used as a gemstone. This silicate is only found in Russia {at the Chary River at Aldan}. Charoite is transparent to translucent and has a hardness of 5.
CHATOYANCY
Chatoyancy is the lustrous, cat's eye effect seen in some cabochon stones, like cat's eye, tiger's eye and sometimes in other stones, like aquamarine. In chatoyancy, light is reflected in thin bands within the stone. Chatoyant stones are cut in cabochon to maximize the lustrous effect.
CHROME DIOPSIDE
Chrome diopside is an emerald-green coloured gemstone. It is a chromium-rich variety of the common mineral diopside {Calcium magnesium silicate}. Chrome diopside has a hardness of 5 to 6 and a specific gravity of 3.3 to 3.6.
CHRYSOBERYL
Chrysoberyl is a hard stone that ranges in colour from yellow, to brown, to green. Some chrysoberyls include alexandritea and cat's eye.
CHRYSOCOLLA
Chrysocolla {meaning "golden lime" in Greek} is an opaque blue to blue-green mineral sometimes used in jewellery. It is usually cut as a cabochon. Chrysocolla {hydrated copper silicate} is found embedded in rock crystal in copper mines in the USA, Russia, Chile, and the Congo. Although Chrysocolla has been used in ornaments since the time of the ancient Greeks, it was only described mineralogically in 1968. Its hardness varies from 2 to 4.
CHRYSOLITE
Chrysolite is a name used for many stones. During Victorian and Edwardian time, it referred to green-yellow chrysoberyl It can also refer to peridot. Long ago, the name was used to refer to almost any yellowish gem.
CHRYSOPRASE
Chrysoprase is the most valued variety of the mineral chalcedony {microcrystalline quartz} that contains nickel, giving it an apple-green colour. Chrysoprase is porous and translucent. It is usually cut as a cabichon, and has been used since ancient times. Chrysoprase has a hardness of 7 and a specific gravity of 2.6. Chrysoprase is mined in Australia, Russia {the Ural Mtns.}, Brazil, and the western USA. Chrysoprase is sometimes called "Australian jade," but it is not related to jade. Hard-to-detect imitation chrysoprase is made by staining agate with chromium salts.
CINNABAR
Cinnabar is the mineral Mercury Sulfide. Its colour ranges from cinnamon to scarlet to brick red and it can be translucent to transparent. It is often carved. Cinnabar has a hardness of 2 - 2.5 (very soft) and a specific gravity of 8.1 (quite heavy)
CITRINE
Citrine {from the French for "lemon"} is a rare, yellow type of quartz, a semi-precious stone that ranges in colour from pale yellow to orange to golden brown. The best quality citrine is found in Brazil. Many of the stones sold as citrine are actually heat-treated amethyst. Citrine has a hardness of 7 and a specific gravity of 2.65.
COGNAC DIAMOND
A cognac diamond is a cognac-brown diamond {having a colour of C7}. Most cognac diamonds are mined in Western Australia {in the Argyle Mine}. The colour is produced by a their low nitrogen content.
CONTRA LUZ OPAL
Contra luz {also spelled contraluz} opals are transparent opals that show a brilliant play of iridescence only when light shines through the stone. When the light is on the same side as the viewer, the iridescence is not readily seen {this quality makes it difficult to design jewellery using these beautiful gemstones}. Contra luz means "against the light." Unlike other opals, contra luz opals are usually faceted {rather than cabochoned}.
CORAL
Coral is an animal that grows in colonies in the ocean. Coral polyps secrete a strong calcium structure that is used in jewellery making. Coral ranges in colour from pale pink {called angelskin coral} to orange to red to white to black. The most valued colours are deep red (called noble coral) and pink. In jewelry making, coral is either carved into beads, cameos, or other forms, or is left in its natural branch-like form and just polished. It used to be thought that coral protected the wearer, so it was a traditional gift to children. Coral has a hardness of about 3.5 and a specific gravity of 2.6 to 2.7. Since it is composed of calcium carbonate, coral will effervesce if touched with acid. Imitation coral is made from glass, porcelain, or plastic.
CORNELIAN
Cornelian {also called carnelian and carneole} is a reddish form of chalcedony {a type of quartz}. This translucent stone has a waxy luster. The best carnelian is from India. Most commercial carnelian is really stained chalcedony. Carnelian has a hardness of 7 and a specific gravity of 2.61.
CORUNDUM
Corundum is a very hard mineral {hardness 9}; only diamond is harder. Corundum is called ruby or sapphire, depending on the color {which depends on which metallic oxides are present}. In its rare pure form, corundum is colourless and called white sapphire. Rubies contain chromic oxide, blue sapphires contain titanium, yellow sapphires contain ferric oxide. Other impure forms are opaque. Corundum stones can produce beautiful asterisms. The word corundum comes from the Tamil word for ruby. Corundum has a specific gravity of 3.96-4.01.
CRYSTAL {GLASS}
Crystal is high-quality glass containing at least 10% lead oxide. Lead added to the melt produces very clear glass resembling rock crystal. The process of making lead crystal was discovered by the English glassmaker George Ravenscroft in 1676. Crystal is colored by adding various metallic oxides to the melt.
CUBIC ZIRCONIUM
Cubic zirconium {also known as cubic zirconia} is an inexpensive, lab-produced gemstone that resembles a diamond. Cubic zirconia was developed in 1977.
CULTURED PEARL
Cultured pearls are pearls produced by oysters that have been surgically injected {nucleated} with bits of mussel shell. After 5-7 years, the oysters are retrieved and the pearls are harvested. This method of "manufacturing" pearls was invented in 1893 by Kokichi Mikimoto.
DANBURITE
Danburite {Calcium borosilicate - CaB2Si2O8} is a clear to white silicate mineral whose orthorhombic crystals are transparent to translucent {danburite can also be yellow, greenish, or brown}; it resembles topaz. It was named for the city of Danbury in Fairfield County, Connecticut, USA {where the original specimens were found in 1839}. Danburite is also found in Russell, New York {USA}, Charcas and San Luis Potosi {Mexico}, Kyushu Island {Japan}, Madagascar, Siberia, Mogok {Myanmar}, Bolivia, and Uri {Switzerland}. Danburite has a hardness of 7 - 7.3 and a specific gravity of 2.97 - 3.02. Its streak is white.
DEMANTOID GARNET
Demantoid garnets are valuable green, very lustrous garnets with a cubic crystalline structure. They are a rare variety of andradite. Demantoid garnets have characteristic inclusions that look like horsetails. Demantoid garnets have a hardness of 6-7 and a specific gravity of 3.8 - 3.9. Demantoids were very popular in the 1800's, but are rarely used today.
DENIM LAPIS
Denim lapis is a relatively pale, inexpensive variety of lapis lazuli that is from Chile. It is the colour of denim cloth due to calcite inclusions {which whiten the stone and lower its value}.
DIAMOND
Diamonds are precious, lustrous gemstones made of highly-compressed carbon. Diamonds are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 - 2.419. Colours of diamonds range from colourless, yellow, orange, brown, to almost black. Rarer colours are red, blue, green, and purple; these colours {called fancies} are quite valuable. Canary diamonds have a deep yellow colour. A diamond's value is based on the "4 C's": colour, cut, clarity, and carat weight. A diamond's colour {saturation} is rated on an alphabetical scale ranging from D {white} to Y {yellow}. "Z" diamonds are fancy, or deep-coloured diamond. A diamond's cut is designed to maximize the stone's natural "fire"; brilliant cuts are preferred. A diamond's clarity depends on the number and size of its flaws and inclusions {of other minerals, like quartz}. Clarity is rated from FI {flawless}, IF {flawless at 10x magnification}, a series of V ratings {very small flaws at 10x magnification}, a series of S ratings {small flaws at 10x magnification), to I1, I2, and I3 {having inclusions visible to the naked eye}. A diamond's carat weight is simple how much it weighs {a carat is about 0.2 grams or about 0.007 ounces}. The largest-known gem-quality diamonds include the Cullinan {aka the Star of Africa, 530.20 carats}, the Excelsior, the Great Mogul {an ancient Indian diamond which is said to have originally weighed 787.5 carats, but its location is not not known and nothing about it has been authenticaed}, the Darya-i-Nur, the Koh-i-Nur, and the Hope diamond {named for a purchaser, Henry Thomas Hope}.
DICHROISM
Dichroism is the property of having more than one color, especially when viewed from different angles. Many minerals {like rubies and axinite} are naturally dichroic. This effect can be artificially caused by a thin layer of a metallic oxides that is deposited on the surface of a material. Dichroic coated glass transmits some wavelengths of light and reflecting others, giving it an opal-like appearance.
DOLOMITE
Dolomite {calcium magnesium carbonate, CaMgCO3} is a common type of sedimentary rock. Dolomite occurs in crystals and in masses. This mineral was named for the French mineralogist Déodat de Dolomieu {1750-1801}, who first described it in 1791.
DRUZE
Druze is a layer of crystals that form within a mineral crust, like the inner cavity of a geode. Amethyst crystals are often found in a druze. The inner cavity of agate geodes are often lined with a druze of sparkling quartz crystals.
DUMORTIERITE
Dumortierite {Aluminum Boro-silicate Hydroxide} is a blue to violet silicate mineral that is used as an ornamental stone {and sometimes as a semi-precious stone in jewellery}. Dumortierite quartz is a massive variety of opaque quartz that is intergrown with dumortierite crystals. Dumortierite has a hardness of 7 - 8.5 and a specific gravity of 3.3 - 3.4.
EBONITE
Ebonite {also called vulcanite} is a hard, moldable, polished dark colored {ranging from brown to black} early rubber. Ebonite was produced by adding sulfur to vulcanized rubber. It was used for combs, ornaments, and buttons. Ebonite is sometimes confused with gutta percha.
EBONY
Ebony is a hard, dark, dense wood sometimes used in jewellery.
EILAT STONE
Eilat stone is only found in King Solomon's copper mines on the Red Sea, near Eilat, Israel. This opaque green mineral is composed of azurite, malachite, turquoise,and chrysocolla. The hardness of this copper-based stone varies. There are many variations on its spelling, including Eliat, Elat, and Ellat.
EMERALD
Emeralds are a very hard, green precious stone (beryl, Be3Al2Si6O18, colored by chromium and some vanadium impurities). Flaws and cloudiness (called jardin) are very common in emeralds, so many emeralds are oiled, irradiatied,and dyed to improve their look. Synthetic emeralds (developed by Carroll Chatham in the 1930's) have fewer imperfections and are very hard to distinguish from natural emeralds. Emeralds belong the beryl group of stones which also includes aquamarines, morganite, and chrysoberyl ). Emeralds have a hardness of 7-8 and a specific gravity of 2.6 - 2.8. Emerald (and all forms of beryl) have large, perfect, six-sided crystals. Emeralds were long thought to have healing powers, especially for eyesight. During the renaissance, emeralds were used as a test for friendship among the aristocracy; an emerald given to a friend would remain perfect as long as the friendsip endured.
EXCELSIOR DIAMOND
The Excelsior is the second- or third largest diamond (depending on whether or not the Braganza diamond was actually a diamond). This irregular-shaped blue-white diamond was roughly 995 carats.. It was found in l893 by a worker at the De Beers mine at Jagersfontein, Orange Free State, South Africa. The Excelsior diamond was cut in 1904 by I.J. Asscher and Company of Amsterdam into 21 stones, including a 69.80-carat marquise, an 18-carat marquise stone (which was displayed at the l939 World's Fair by the De Beers company), and many other stones.
FIRE OPAL
Fire opals are a type of opal that is firey orange to red in color (but have no opalescence). These opals are rarely transparent - they are usually milky. Opal is a mineral composed of silica (and some water) and is a species of quartz. Many opals have a high water content - they can dry out and crack if they are not cared for well (opals should be stored in damp cotton wool). Opals have a hardness of 5.5 to 6.5 and a specific gravity of 1.98-2.50. Fire opals are found in Western Australia, Mexico, Brazil, Guatemala, and Honduras.
FLOWERING OBSIDIAN
Flowering Obsidian (also called snowflake obsidian) is a volcanic glass that is usually dark (black or brownish) with white "snowflakes". This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Obsidian is formed when viscous lava (from volcanos) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35.
FLUORITE
Fluorite is a mineral that comes in many colors, including purple, clorless, red, pink, yellow, green, blue, black, and multi-colored stones. Crystals are transparent to translucent. Fluorite is relatively soft - it has a hardness of 4 and a specific gravity of 3.0 - 3.3. The chemical formula for fluorite is CaF2. Fluorite is frequently fluorescent (various varieties fluoresce red, blue, green or yellow light). Fluorite is found all around the world. Some varieties of fluorite include: Blue John (purple with bands of white or yellow), Chlorophane (thermoluminescent - emitting bright green light when heated), Yttrofluorite (yttrium replaces some of the calcium - formula = [Ca,Y]F2), Yttrocerite (cerium and yttrium replaces some of the calcium in its structure - formula = [Ca,Ce,Y]F2, Antozonite (contains uncombined fluorine ions - when fractured or cleaved, it gives off an odd odor).
FRENCH IVORY
"French Ivory" is synthetic (imitation) ivory, It is molded from plastics (like celluloid) and is also called Ivoride, Ivorine, and "Genuine French Ivory."
FRENCH JET
French jet is black glass (pyrolusite glass) designed to imitate real jet. It was frequently carved.
FRESHWATER PEARL
A freshwater pearl is a pearl that was harvested from a freshwater mussel (a mollusk). These pearls are frequently shaped like crisped rice cereal, and are less valuable than oyster pearls. Biwa pearls are very good quality freshwater pearls.
FROST AGATE
Frost agate is agate with white markings (that look like frost).
FUCHSITE
Fuchsite is a deep emerald green variety of the mineral muscovite that is rich is the chromium. It has a glassy luster. Fuchsite is relatively soft; it has a hardness of 2-2.5 and a specific gravity of 2.77-2.88. The chemical formula for fuchsite is K(Al,Cr)2(AlSi3O10)(OH)2.
GAGATE
Gagate (popularly known as jet) is fossilized coal. It is a hard, lustrous black stone that was used in mourning jewelry during the Victorian era (especially after Queen Victoria's husband died and she went into a long-lasting mourning, affecting fashion). Jet is frequently cabochon cut. Gagate has been mined near Whitby (on the Yorkshire coast of England) since prehistoric times. It is also found in Spain. France, Germany, and Russia, but these other sources are said to be inferior to the harder, more elastic Whitby jet. Jet/gagate has a hardness of 2.5-4 (quite soft) and a specific gravity of 1.30-1.35 (it is relatively lightweight). Jet leaves a brown streak. When burnt with a red-hot needle, jet smells like coal Black glass and plastics are often used to imitate jet (glass is much heavier and harder than jet) - jet is warm to the touch.
GAHNOSPINEL
Gahnospinel is a rare blue spinel stone that is high in zinc and magnesium. It can only be distinguished from most spinel by its high specific gravity and high refractive index. Gahnospinel has a hardness of 8, a specific gravity of 3.97. Its chemical formula is (Mg, Zn)Al2O4.
GARNET
Garnets are any of a group of semi-precious silicate stones that range in color from red to green (garnets occur in all colors but blue). Some garnets used as gemstones include pyrope (the deep red garnet), almandine, spessartine, grossular, the iron-aluminum dark red garnet (also known as the carbuncle stone), Uvarovite (rare), and the lustrous Andradite (which includes the valuable green demantoid garnet, Topazolite , and Melanite). Red garnet is the birthstone for January. Garnet has a hardness of 6-8 and a specific gravity of 3.5 - 4.3. The formula for garnet is: (Mg, Fe, Ca or Mn) with Al2Si3O12.
GASPEITE
Gaspeite is a pale green to apple-green semi-precious gemstone that often has brown inclusions of its host rock. Gaspeite is translucent to opaque. This beautiful stone has only recently been used in jewelry, and is often set in silver. Gaspeite has a hardness of 4.5 - 5, and a specific gravity of 3.7. Gaspeite is Nickel Magnesium Iron Carbonate; its chemical formula is (Ni, Mg, Fe)CO3. This stone is found in Gaspe Peninsula, Quebec, Canada (where it was originally found and from which it derives its name) and Kambalda and Widgie Mooltha, Western Australia, Australia.
GEODE
A geode is a rock whose crystal-filled interior can be hollow or filled. The crystals that form within the mineral crust of the geode is called druze. From the outside, geodes look like rounded, but otherwise ordinary rocks.
GOSHENITE
Goshenite is the pure, colorless form of beryl (Be3AlSiO6, related to emerald and aquamarine). This hard, transparent gemstone is named for the town of Goshen, Massachusetts, where it was first found. Goshenite has been found in North and South America (especially Colombia), Northern Europe, East Africa, South Africa, and the Himalayan mountains in Asia. Goshenite has a hardness of 7.5 - 8.0 and a specific gravity of 2.6 - 2.8. It is not enhanced. Goshenite is sometimes coated with a green foil to resemble an emerald
GRAPE GARNET
Grape garnets are a rare, intense violet to purple-red garnet. Grape garnets are made up of almandite and spessartite. They have a hardness of 7-7.5 and a specific gravity of 3.8 - 3.9. Grape garnets are found in the Orissa district of northwestern India.
GREEN DIAMOND
Green diamonds are rare, fancy diamonds and are quite valuable. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 - 2.419.
GREEN GARNET
Green garnets are Demantoid garnets, a valuable green, and very lustrous type of garnets. They are a rare variety of andradite. Demantoid garnets have characteristic inclusions that look like horsetails. Demantoid garnets has a hardness of 6-7 and a specific gravity of 3.8 - 3.9. Demantoids were very popular in the 1800's, but are rarely used today.
GREENSTONE
Greenstone is another name for nephrite, a semi-precious stone and a variety of jade. Nephrite is slightly softer that jadeite and is often veined; it is used in carvings, for making beautiful bowls and vases.
GRIQUALANDITE
Griqualandite is tiger's eye from Griqualand, South Africa. It is a yellowish-brown to reddish-brown gemstone that has a silky luster. This gemstone has bands of yellow and brown; when viewed from the opposite direction, the colors are reversed. Tiger's eye is usually highly polished and set as a cabochon (or cut as a bead) to display the stone's chatoyancy (light reflected in thin bands within the stone). Tiger's eye is a type of chatoyant quartz with fibrous inclusions (especially crocidolite). This stone is sometimes heat treated. Tiger's eye has a hardness of 7.0.
GROSSULAR GARNET
Grossular garnet is a type of garnet, calcium-aluminum silicate. Hessionite is a transparent brown, yellow, orange, or honey-colored variety of grossular garnet often used in jewelry. The yellow variety is called cinnamon stone, hyacinth or jacinth. Transvaal "jade" is a type of green to gray grossular garnet from South Africa. Pink grossular garnets varieties include landerite, rosolite, and Xalostocite. Tsavorite is an emerald-green grossular garnet. Grossular garnet has a hardness of 6-7.5 and a specific gravityof 3.6.
HAWK'S EYE
Hawk's eye is a green, grey or blue variety of quartz that has parallel, fibrous inclusions of crocidolite that give it a greenish cat's eye effect ( chatoyancy ). This mineral has a silky luster. It looks a lot like tiger's eye, and often occurs with it in the same rock, but the internal structure is different.
HELIOTROPE
Heliotrope (commonly known as bloodstone) is an inexpensive type of chalcedony that is green with red highlights (caused by iron oxide). Heliotrope is porous and relatively soft.
HEMALYKE
Hemalyke is a synthetic hematite that is made by grinding up hematite, adding a binder (glue) and then press-molding it. The stone is sometimes faceted. Hemalyke looks very much like natural hematite - it is very difficult to them apart.
HEMATITE
Hematite (sometimes spelled haematite, and also known as kidney ore) is a lustrous, opaque, blue-black to silvery gray mineral often used in jewelry. Hematite is iron oxide (Fe2O3). Hematite has a hardness of 6.5 and a specific gravity of 4.95 to 5.16. When powdered, hematite is red; when rubbed on a hard stone, it leaves a red streak. Hematite was often used as seal stones, cut as intaglio. It is also used as beads and is faceted, carved or cut as a cabochon for use as a gemstone. The ancient Egyptians carved hematite into scarabs. Hematite is found in England, Mexico, Australia, Brazil, and the Lake Superior region of North America.
HERKIMER DIAMOND
Herkimer diamonds are clear, lustrous, doubly terminated crystals of quartz - they are not true diamonds. These brilliant stones are also called "Middleville Diamonds" or "Little Falls Diamonds." Herkimer diamonds have a hardness of 7. This stone is found in Middleville and Little Falls, Herkimer County, New York, USA.
HESSONITE
Hessonite (also called "cinnamon stone") is a cinnamon-brown to orange gemstone variety of grossular garnet. Hessonite's formula is Ca3Al2Si3O12; manganese that gives it its characteristic brown color. This transparent stone has a hardness of 6.5 - 7 and a specific gravity of 3.6. Hessonite is found in Sri Lanka, Brazil, Madagascar, Canada, and California, USA. This stone is not enhanced.
HOWLITE
Howlite is a soft, white to gray mineral that takes dye very easily, and can be dyed to imitate turquoise very well (and is sometimes unscrupulously sold as turquoise). Howlite was named for its discoverer, Henry How, a Nova Scotia geologist.
HYACINTH
Hyacinth is a semi-precious stone that is also known as jacinth. it is a lustrous orange-yellow, orange-red, or yellow-brown type of zircon. Hyacinth has a hardness of 7.5 and a specific gravity of 4.65. Sometimes, topaz and grossular garnet of this color are also referred to as hyacinth (this can be very confusing). Hyacinth is mined in Sri Lanka. Even more confusing is the origin of the name, which comes from the Greek hyakinthos, which refers to blue gemstone.
HYACINTH OPAL
Hyacinth opal (also known as girasol) is a yellow or orange type of precious opal. In this opal, the play of colors seems to come from within the stone, like a floating light, and seems to follow the light source.
INDICOLITE
Indicolite is a green to blue-green variety of tourmaline.
IOLITE
Iolite (meaning 'violet stone'), also known as water sapphire and lynx sapphire, is a transparent, violet-blue, light blue, or yellow-gray mineral. Iolite is pleochroic, a single stone will show many colors (in the case of Iolite, violet-blue, light blue, and yellow-gray). Iolite is not rare and has a hardness of 7 - 7.5. Iolite is found in Sri Lanka, India, Madagascar and Burma.
IVORY
Ivory is elephant tusks (the large, upper incisor teeth), which used to be carved into beautiful jewelry, trinkets, and piano keys. The finest ivory is the white African elephant ivory; Asian elephant ivory is yellower. Ivory has a complex characteristic grain which helps distinguish it from imitations. Using ivory is now banned since elephants are in danger of going extinct. Other tusk-like material is often substituted for ivory, including walrus tusks, whale teeth, hippopotamus teeth, animal bone, palm seed, and more recently, plastics. Vegetable ivory comes from the inner seed of the South American ivory palm and was used for small items, like dice. Synthetic ivory is made from plastics (like celluloid) and is called "French Ivory," Ivoride, Ivorine, or "Genuine French Ivory."
JACINTH
Jacinth is a semi-precious stone that is also known as hyacinth. it is a lustrous orange-yellow, orange-red, or yellow-brown type of zircon. Hyacinth has a hardness of 7.5 and a specific gravity of 4.65. Sometimes, topaz, and grossular garnet of this color are also referred to as hyacinth (this can be very confusing). Hyacinth is mined in Sri Lanka. Even more confusing is the origin of the name, which comes from the Greek hyakinthos, which refers to blue gemstone.
JADE
Jade is a semi-precious stone that ranges in color from green to white to lilac to brown to almost black. Translucent jade is more highly valued than opaque jade. Jade is often cabochon set; stones with imperfections are often carved (the imperfections are simply carved away). Two different minerals are known as jade: jadeite and nephrite. Jadeite is the harder of the two; it is usually used in jewelry production. Nephrite is slightly softer and is often veined; it is used in carvings, for making beautiful bowls and vases. The Chinese have prized jade for thousands of years and regarded it as having medicinal properties when worn or ingested as a powder. Natural jadeite is called Type A or Grade A jade (waxing or wax dipping is allowed). Jadeite that had been bleached and then treated with polymers (plastic) or waxes is called Type B or Grade B jade (it is less durable than natural jade). Jadeite that had been dyed is called Type C or Grade C jade (the color is less durable than that of natural jade). Jadeite that has been both dyed and impregnated with polymers is called Type B+C or Grade B+C.
JADEITE
Jadeite is the harder of the two varieties of jade. Jadeite is harder (compared to nephrite) and is usually used in jewellery production.
JASPER
Jasper is a common, opaque, semi-precious stone that is found in many colors, including white, brown, yellow, red, and green. Jasper is found all over the world; it is often striped, speckled, and multi-colored. Jasper has been used for intaglio carvings. Jasper is a type of quartz, belonging to the chalcedony family. It is often sealed with petroleum products. Jasper is sometimes dyed to resemble lapis lazuli and misleadingly called "Swiss lapis." Jasper has a hardness of 6.5 to 7.0.
JET
Jet (also known as gagate) is fossilized coal. It is a hard, lightweight lustrous black stone that was used in mourning jewelry during the Victorian era (especially after Queen Victoria's husband died in 1861 and she went into long period of mourning, greatly affecting jewelry fashion). Jet is frequently cabochon cut. Most jet is from Whitby, England; jet has been mined near Whitby (on the Yorkshire coast of England) since prehistoric times. It is also found in Spain, France, Germany, and Russia, but these other sources are said to be inferior to the harder, more elastic Whitby jet. Jet has a hardness of 2.5-4 (quite soft) and a specific gravity of 1.30-1.35 (it is relatively lightweight). Jet leaves a brown streak, When burnt with a red-hot needle, jet smells like coal. Black glass and plastics are often used to imitate jet (glass is much heavier and harder than jet) - jet is warm to the touch.
KUNZITE
Kunzite is a transparent pink, light pink, or light purple gemstone that resembles roze quartz. It is a variety of the mineral spodumene. Kunzite can fade after prolonged exposure to light. Kunzite is also called "evening stone," because of its propensity to fade in bright light. The original color of some kunzite stones can be restored or even intensified by irradiation. It is usually used as a large stone and is easily chipped; small stones of kunzite are difficult to cut. Kunzite is often used in pendants. Kunzite has a hardness of 6-7 and a specific gravity of 3.1 - 3.2. Kunzite was first found in 1902 in Pala, California, USA, and is named for the gemologist George F. Kunz. Kunzite's chemical composition is LiAlSi2O6,
KYANITE
Kyanite is a deep sapphire blue, green, gray, or white gemstone. The color is not always uniform; it can be blotchy or in streaks. The cystals are crystals are transparent to translucent. Kyanite has a hardness of 4.5 to 6.5; the hardness varies depending on which way it is scratched (this happens because kyanite consists of long, thin crystals). It has a specific gravity of 3.58. Kyanite is found in Brazil, Burma, Kenya, Europe, India, Australia, Kenya, and the USA. Kyanite's chemical composition is Al2SiO5; it is composed of andalusite and sillimanite.
LABRADORITE
Labradorite (a variety of plagioclase feldspar) is a fairly abundant grayish mineral that has brilliant flashes of color (usually green, blue or red) after it is polished (called labradorescence). The crystals are transparent to translucent. There is a darker variety of labradorite (called "black moonstone") which has bluish inclusions. Labradorite is usually cut with a flat surface in order to highlight the flashes of color. Labradorite was originally found along the coast of Labrador about 1805; it is also found in Newfoundland, other parts of Canada, also known as spectrolite, the Ukraine, the Ural mountains, and the USA. Labradorite has a hardness of 6 to 6.5 and a specific gravity of 2.70. Finnish labradorite is also known as spectrolite.
LAPIS LAZULI
Lapis lazuli is a rich blue opaque, semi-precious stone that has been used in jewelry since ancien times. Ground-up lapis lazuli was once used as a pigment for oil paintings. Lapis lazuli is often dyed to deepen and improve its color. Lapis has a hardness of 5.5; it chips and scratches easily. It has a specific gravity of 2.4 to 2.9. Water can dull its sheen. Lapis lazuli contains the minerals calcite (which decreases its value), pyrite (which can increase its value), and sodalite. Swiss lapis is not Lapis lazuli at all; it is dyed jasper. Denim lapis is relatively pale, low-grade, inexpensive lapis from Chile; it is the color of denim cloth because of calcite inclusions (which whiten the color and lower the value).
LAVA
Lava from the volcano Vesuvius near Pompeii in Italy has been used to make jewelry, especially cameos. Lava jewelry was popular in the nineteenth century.
MAHOGANY OBSIDIAN
Mahogany Obsidian (also called Apache tears) is brownish obsidian. This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Obsidian is formed when viscous lava (from volcanos) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35.
MALACHITE
Malachite is an opaque semi-precious stone with layers of deep green and light green. It is usually found in copper mines; malachite is about 57% copper. Malachite was used as jewelry thousands of years ago by the ancients Egyptians. Malachite is usually cabochon set in silver. Russian malachite carvings were done in miniature and in large scale; malachite was also inlaid in furniture. Malachite has a hardness of 4 and a specific gravity of 3.80. It is monoclinic, it has one two-fold axis of symmetry. Malachite is sometimes coated with colorless wax, oil, or hardening agents to increase its durability and enhance its appearance.
MARCASITE
Marcasite is a shiny, metallic semi-precious stone. It is actually iron pyrite. Marcasite is generally faceted.
MAW-SIT-SIT
Maw-sit-sit is a rare green gemstone that has dark-green to black veining; it sometimes has white spots. The stone is opaque to translucent. Maw-sit-sit has a hardness of 6.0; the specific gravity is 2.5 to 3.5. This stone is found in Maw-sit-sit, Myanmar (Burma), and is often found neat jadeite, but maw-sit-sit is not a type of jade. Maw-sit-sit was first identified in 1963 by the Swiss Gemologist Eduard Gübelin; the local called the stone maw-sit-sit, and the name was retained. Although its exact composition is still unknown, Maw-sit-sit is composed of chromite, ureyite, chrome jadeite, symplektite, chrome amphibole, and other lighter minerals.
MICA
Mica is a soft, lightweight, transparent mineral that cleaves into thin, elastic sheets (it has a single perfect cleavage direction). It is used for lampshades and electrical insulators. There are about 30 different types of micas, ranging in color from yellow to green to gray to violet to white to brown. Mica has a hardness of 2.5 and a specific gravity of about 3. Tiny mica particles give the shimmer to aventurine ( goldstone )
MICROCRYSTALLINE
Microcrystalline is a type of mineral structure in which the crystals are so small that they can only be seen using a microscope.
MOISSANITE
Moissanite is a very hard mineral that was discovered by Dr. Ferdinand Henri Moissan (1852-1907), a French chemist and Nobel Prize winner (Moissan did work on synthesizing diamonds and discovered carborundum in 1891). He found tiny amounts of Moissanite in the iron meteorite that was found at Diablo Canyon (also called Meteor Crater) in Arizona, USA. Moissanite ranges in color from colorless to blue to green to yellow. Its chemical makeup is Silicon Carbide (SiC); it is also called Carborundum. Moisannite crystals are transparent to translucent. Moissanite has a hardness of 9.25 (this is almost as hard as diamond) and a specific gravity of 3.1 - 3.2. Laboratory-grown Moissanite is sold as a gemstone.
MOLDAVITE
Moldavite is a rare, glassy, translucent, dark green gemstone. Moldavite is a silica-based tektite, a mineral formed when a meteorite (a rock from space) struck the Earth's surface and melted and fused the surrounding rock. Moldavite is only found in Bohemia (the Czech Republic) in the Ries Crater in the Moldau River valley (which it was named for). Moldavite was discovered in the late 1800's; the meteorite from which it formed hit the Earth about 14.7 million years ago. Moldavite has a hardness of 5.5-6.6. Inclusions of gas bubbles and iron/nickel spherules are common. This natural glass has been used for jewellery, religious articles, and decorative objects since prehistoric times.
MONOCLINIC
Monoclinic minerals have a crystalline structure in which there is one two-fold axis of symmetry. Jade, Malachite and Moonstone are monoclinic.
MONTANA RUBY
A Montana ruby is actually a pyrope garnet (and not a ruby at all).
MOONSTONE
Moonstone (orthoclase) is a semi-translucent stone that is made of albite and orthoclase feldspar. It is usually whitish-blue, but can be colorless, yellow, orange, gray, or even reddish. Moonstone is usually set as a cabochon. Moonstone was very popular early in the 20th century and was extensively used in Art Nouveau jewellery. Moonstone has a hardness of 6 and a specific gravity of 2.57. It is monoclinic; it has one two-fold axis of symmetry. Adularia is a common type of moonstone. Oligoclase is another type of moonstone; Labradorite and albite are rare forms.
MORGANITE
Morganite is a transparent to translucent pink gemstone. It is a variety of beryl, Be3Al2(Si6O18) that contains some manganese (giving the stone its pink color). Morganite has a hardness of 7.5 - 8 and a specific gravity of 2.71 - 2.90. It has poor cleavage and is brittle. Morganite is often heat treated to give the stone a purer pink color (and remove any yellow spots). Morganite was named for J. Pierpoint Morgan, the American industrialist and gem collector. Morganite is found in Brazil, Madagascar, Italy, Pakistan, Mozambique, Namibia, Zimbabwe, and the USA (California, Maine, Connecticut, and North Carolina).
MOSS AGATE
Moss agate (also called Mocha stone in Britain and the USA) is a green variety of agate. It is chalcedony that has dendritic (tree-like) inclusions of green (red or black) hornblende. The inclusions often form beautiful patterns. Moss agate has a hardness of 6.5-7 and a specific gravity of 2.6. Green moss agate is found in India, and some other locations.
MOTHER-OF-PEARL
Mother-of-pearl is the iridescent coating on the inside of oyster shells. Mother-of-pearl is used for jewellery, buttons, and other uses.
MOUKAITE
Moukaite is a semi-precious gemstone, a variety of jasper from Australia. The color of moukaite varies from red-browns to pinks, with gold and white bands,
MYSTIC FIRE
Mystic fire (also called mystic topaz or rainbow topaz) is topaz that has been color enhanced by coating it with a fine layer of metal atoms (in a process called vacuum deposition). This stone has red, green, violet, and blue streaks. Mystic fire has a hardness of 8.
NACRE
Nacre is a usually whitish crystalline substance which oysters, mussels, snails, and other mollusks secrete around a foreign object (like a tiny stone) that has made its way into their shell. As layers of nacre coat the intruder, a pearl is formed over a period of many years.
NATURAL PEARL
A natural pearl (also called a genuine pearl) is a pearl that was produced in an oyster, freshwater mussel or other mollusk as a reaction to a tiny invading object that happened to be caught inside its shell.
NEPAL DIAMOND
Nepal diamond is a huge flawless, pendeloque diamond that probably came from the Golconda mines in India. The Nepal diamond weighs 80 carats. It was originally owned by the Nepalese government but is now owned by Harry Winston, an American jeweler.
NEPHRITE
Nephrite is a semi-precious stone, a variety of jade (sometimes called greenstone). Two different minerals are known as jade, jadeite and nephrite. Nephrite is slightly softer that jadeite and is often veined; it is used in carvings and for making beautiful bowls and vases.
OBSIDIAN
Obsidian (also called Apache tears) is a volcanic glass that is usually black, but is occasionally red, brown, gray, green (rare), dark with "snowflakes," or even clear. This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Obsidian is formed when viscous lava (from volcanos) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35.
OILING
Oiling is a process of applying mineral oil to a stone in order to enhance it and mask inclusions, make them more transparent, and darken their color. Emeralds are frequently oiled to mask their many inclusions.
OLD ROCK TURQUOISE
Old rock turquoise is an old Persian (Iranian) turquoise term for very high quality turquoise (sky blue, veinless turquoise that retains it color).
ONYX
Onyx is a semi-precious stone that is black and white, generally arranged in layers. It is a form of agate with parallel banding. This structure lends itself to cameo making. Onyx is a species of chalcedony (microcrystalline quartz).
OPAL
Opals are semi-precious stones that are luminous and iridescent, frequently with inclusions of many colors ("fire"). Opal is a mineral composed of noncrystalline (amorphous) silica (and some water) and is a species of quartz. There are three major types of opals: common opal, opalescent precious opal (white or black, with a rainbow-like iridescence caused by tiny crystals of cristobalite), and fire opal (a milky stone that is firey orange to red in color with no opalescence). Contra luz opals are transparent opals that show a brilliant play of iridescence only when light shines through the stone. Many opals have a high water content - they can dry out and crack if they are not cared for well (opals should be stored in damp cotton wool). Some opals are treated with oil, wax or resin to enhance their finish. Opals have a hardness of 5.5 to 6.5 and a specific gravity of 1.98-2.50. Opals are found in many places worldwide, including Kenya, Czechoslovakia, Brazil, Peru, Honduras, Mexico, Canada, and the USA -- but Australia has a tremendous variety of beautiful opals.
OPAL DOUBLET
An opal doublet is a manufactured stone that is composed of two thin layers that are glued together. A thin layer of opal is glued on top of another mineral (usually a black onyx or ironstone, which enhances the stone's color), producing a stone that is less expensive than a solid opal.
OPERCULUM
The operculum is part of many shelled animals - it is the calcified, disc-shaped "trap door" that opens and closes to protect the animal inside its shell. The operculum from a species of sea snail called the Turban Shell (Turbo petholatus, found in the South Seas north of Australia) is eye-like with a natural cabochon shape and is used in jewelry. This jewellery was popular in Victorian Era Britain. Operculum is also called Pacific Cat's-eye.
PACIFIC CAT'S EYE
Pacific Cat's-eye is the operculum of a sea snail called the Turban Shell (Turbo petholatus, found in the South Seas north of Australia). The operculum is part of many shelled animals - it is the calcified, disc-shaped "trap door" that opens and closes to protect the animal inside its shell. The Turban Shell's operculum is an eye-like disc with a natural cabochon shape - it is used in jewelry.
PADPARADSCHA SAPPHIRE
Padparadscha sapphires (also spelled padparadschah) are a rare pink-orange variety of corundum or the synthetic equivalent. These gems are mined in Sri Lanka and are usually heat treated to improve and intensify the color. The name padparadscha comes from the Sinhalese word for lotus flower. Hardness = 9, Specific gravity = 4,
PEARL
Pearls are organic gems grown within oysters and a few other mollusks. Pearls are formed when a foreign object (like a tiny stone) has made its way into the mollusk's shell. The mollusk secretes nacre, a lustrous substance that coats the intruding object. As thousands of layers of nacre coat the intruder, a pearl is formed; this process takes up to seven or eight years (an oyster's useful life span). The most valuable pearls are perfectly symmetrical, large, naturally produced, and have a shimmering iridescence (called orient luster). There are many types of pearls, including natural pearls (made with no human interference), cultured pearls (pearls made by inserting a bit of a mother-of-pearl) into [nucleating] a living oyster or by inserting a bit of foreign tissue), baroque pearls (irregularly-shaped pearls), freshwater pearls, seed pearls (tiny pearls), Biwa pearls (a type of freshwater pearl from Lake Biwa, Japan from the freshwater mussel, Hyriopsis schlegeli), blister pearls (grown attached to the shell), black pearls (gray to black pearls), Mabe pearls (cultivated blister pearls), etc. Pearls can be gently cleaned with mild soap and water. The biggest natural pearl, known as the "Pearl of Allah" or "Pearl of Lao-tse," weighs 14 pounds (6.4 kg).
PERIDOT
Peridot (also known as the "evening emerald" and chrysolite ) is a yellow-green semi-precious stone with an oily luster; peridot is a transparent, green form of olivine. Peridot exhibits double refraction; when you look through the stone, things appear double. For example, when looking into a faceted peridot gemstone, the number of bottom facets appears to be double the actual number of facets. Most peridots are from a volcanic island in the Red Sea, Zebergit/St. John, the "Serpent Isle." Peridots have been found in meteorites. Peridot has a hardness of 6.5. Peridot cat's eye also exists.
PETRIFIED WOOD
Petrified wood (also called xyloid jasper or jasperized wood) is wood that has fossilized - all the original chemicals in the wood have ben replaced with minerals, making a stone-like replica of the original wood.
PINK TOPAZ
Pink Topaz (Aluminum silicate fluoride hydroxide) is a very hard pink gemstone. Pink topaz is usually created by irradiating common yellow topaz. Topaz has a hardness of 8 and a specific gravity of 3.5-3.6.
PURPLE DIAMOND
Purple diamonds are rare, fancy diamonds and are quite valuable. Diamonds are precious, lustrous gemstones made of highly-compressed carbon; they are one of the hardest materials known. Diamonds have a hardness of 10, a specific gravity of 3.5, and a refractive index of 2.417 - 2.419,
PYROPE GARNET
Pyrope garnet is the familiar deep red garnet. Red garnet is the birthstone for January. Garnet has a hardness of 6-8 and a specific gravity of 3.5 - 4.3. The formula for garnet is: A3B2(SiO4)3. Pyrope garnet is also called (misleadingly) American Ruby, Arizona Ruby, Australian Ruby, Bohemian Ruby, California Ruby, Cape Ruby, Colorado Ruby, Elie Ruby, Montana Ruby, and Rocky Mountain Ruby.
PYRITE
Pyrite (also known as fool's gold) is a shiny, metallic mineral that is a form of iron. Marcasite stones come from pyrite
QUARTZ
Quartz is a crystalline mineral that come in many forms, including amethyst, aventurine, citrin, opal, rock crystal, tiger's eye, rose quartz and many others. Rutilated quartz and tourmalinated quartz have needle-like inclusions of other minerals. Quartz has a hardness of 7.0. This common mineral is found worldwide.
QUARTZ DRUZE
Quartz druze is a layer of quartz crystals that form within a mineral crust, like the inner cavity of a geode. For example, the inner cavity of agate geodes are often lined with a druze of sparkling quartz crystals.
QUINZITE OPAL
Quinzite opal is a red to pink type of opal. This opal is also called Quincite, Quincite Opal, and Rose Opal.
RAINBOW CALSILICA
Rainbow calsilica is a newly-found, multi-colored, layered stone composed of calcium and silica. This stone has been recently used for Zuni fetish carvings and in some jewelry (beads and cabochon cut stones). Rainbow calsilica was only recently found in Mexico or Northern South America (it's origin remains mysterious). Some people theorize that this stone formed as a result of the runoff of mining or oil-drilling chemicals, and has only formed in the last 30 to 50 years (but this is uncertain).
RAINBOW OBSIDIAN
Rainbow obsidian is another name for obsidian that is iridescent.
RAINBOW TOPAZ
Rainbow topaz (also called mystic topaz or mystic fire) is topaz that has been color enhanced by coating it with a fine layer of metal atoms (in a process called vacuum deposition). This stone has red, green, violet, and blue streaks. Mystic fire has a hardness of 8.
RED BERYL
Red beryl is a is a rare, deep red variety of beryl. Gemstone-quality forms of this mineral are found in only one place in the world, in the Wah Wah Mountains, near Beaver, Utah, USA. Small crystals of this gem were first found in 1905 in the Thomas Range in Juab County, Utah. The mine bearing gemstone-quality red-beryl was found in the 1950's. The biggest red beryl crystal ever found was 14mm by 34mm, weighing about 54 carats. The average faceted red beryl gemstone weighs about 0.15 carats. Red beryl has a hardness of 7 - 8, a specific gravity of 2.66-2.70, and a refractive index of 1.564-1.574. The chemical formula Be3Al2SiO6, with other trace elements. Internal flaws in beryl gems can be hidden by treating the stone with oil (this is often not disclosed to the buyer).
RHINESTONES
Rhinestones are highly reflective glass made to imitate gemstones. The original rhinestones were quartz stones (rock crystal) obtained from the Rhine river. These stones were cut to resemble gemstones. The best rhinestones today are made of highly reflective leaded glass which is faceted, polished and are made worldwide.
RHODOCHROSITE
Rhodochrosite is a mineral whose color ranges from rose to pink to almost yellow or brown. Although it is very pretty, this stone is soft and brittle; it is used in jewellery and for carvings and figurines. Rhodochrosite is Manganese Carbonate; its chemical formula is MnCO3. Rhodochrosite has a hardness of 3.5 - 4.5 (glass has a hardness of 4) and a specific gravity of 3.5. Rhodochrosite is found in Argentina, Peru, Germany, Mexico, South Africa, Russia, Italy, USA (Colorado and Montana), and Romania. Rhodochrosite is not enhanced.
RHODOLITE
Rhodolite (meaning "rose stone" in Greek) is a purple-red to pink-red variety of garnet. It is a combination of almandine and pyrope (it is sometimes called pyrope-almandine garnet). This silicate stone has a hardness of 7-7.5 and a specific gravity of 3.5 - 4.3. The formula for garnet is: A3B2(SiO4)3. Rhodolite is found in the US, Zimbabwe, Kenya, and Sri Lanka (Ceylon). Rhodolite is not enhanced.
RIVERSTONE
Riverstones are smooth, rounded pebbles found in rivers and on beaches. The action of the water and other rocks on riverstones polishes them naturally. Riverstones can be used as beads/stones in jewellery, popular in Scotland.
ROCK CRYSTAL
Rock crystal is a transparent, crystalline mineral. Rock crystal is the purest form of quartz and a semi-precious stone.
ROSE QUARTZ
Rose quartz is a form of quartz that ranges in color from pink to deep red.
RUBELLITE
Rubellite (sometimes spelled rubelite) is a red variety of Tourmaline. Rubellite is red in both incandescent light and daylight, and is more valuable than other varieties of red tourmaline. Rubellite has a hardness of 7-7.5 and a specific gravity of 3.02-3.25. Rubellite is sometimes treated with fillers to increase the clarity of the stone.
RUBY
Rubies are precious stones and a member of the corundum family (Al2O3). Rubies range in color from the classic deep red to pink to purple to brown. Rubies are extremely hard; only diamonds are harder. During the renaissance, people thought that rubies could counteract poison. Laboratory-produced rubies were created in the 1890's; they are difficult to distinguish from natural rubies. The biggest ruby in the word is the Raviratna, which weighs 3,600 carats. Rubies have a hardness of 9 and a specific gravity of 3.9 - 4.1. Rubies are found in Afghanistan, Australia, Brazil, Cambodia, India, Myanmar (Burma), Malagasy Republic, Malawi, Pakistan, Sri Lanka (Ceylon), Tanzania, Thailand, United States, and Zimbabwe (Rhodesia).
RUBY SPINEL
A ruby spinel (or spinel ruby) is deep red, transparent spinel (not a ruby).
RUTILATED QUARTZ
Rutilated quartz is a type of rock crystal which contains long, fine needles of rutile crystals (titanium dioxide). This beautiful stone is usually cut as a cabochon. It is also known as Venus' Hair Stone, Cupid's darts, and Fleches d'amour (arrows of love).
SAPPHIRE
Sapphire is a precious gemstone (a type of corundum) that ranges in color from blue to pink to yellow to green to white to purple (mauve sapphire) to pink-orange (padparadsha sapphire). Six-sided asterisms sometimes occur in star sapphires (caused by inclusions of tiny, thin, parallel needles of rutile). Sapphires are related to rubies. Sapphires were once thought to protect the wearer from poisonous creatures. Sapphire has a hardness of 9 and a specific gravity of 3.9 - 4.1. Sapphires are often heat treated to improve their color.
SAPPHIRE QUARTZ
Sapphire quartz (also called blue quartz) is another name for blue chalcedony.
SARD
Sard is a semi-precious stone related to carnelian. This brownish-red, opaque gemstone was once used extensively for seals and was carved using intaglio. Sard was named for Sardis, the ancient capital of Lydia. Sardius is mentioned in the Bible, and may refer to jasper.
SARDONYX
Sardonyx is a semi-precious stone that is formed by two layers, a red-brown layer of sard and a gray, white, black or brown layer of onyx. Sardonyx is a type of quartz. Sardonyx is frequently carved to make intricate cameos and seals.
SEFTONITE
Seftonite is a translucent, moss green type of chalcedony. It is found in South Africa and North America.
SELENITE
Selenite is a soft, colorless-to-slightly-colored, transparent mineral. It is a crystalline variety of gypsum. Selenite has a hardness of 1-2 and a specific gravity of 2.3 to 2.4.
SERPENTINE
Serpentine is a green stone; there are two types of serpentine, bowenite and hydrated magnesium silicate. Bowenite is a jade-like stone (green to black) that is sometimes used in jewelry. The softer variety, hydrated magnesium silicate, is translucent serpentine has a hardness of 4 () - 5.5 (bowenite) and a specific gravity of 2.5 to 2.6. Serpentine is found in the British Isles and some other locations. Connemara marble (from Ireland) is a type of cloudy green serpentine.
SILLIMANITE
Sillimanite (aluminum silicate, Al2 SiO5) is a transparent to translucent mineral that ranges in color from white to gray to brownish to greenish. Sillimanite has the same chemical formula as both kyanite and andalusite (these three minerals are polymorphs); Sillimanite is the rarest of the three (all three are used in high-temperature ceramics, used in spark plugs). Sillimanite has a hardness of 7.5 and a specific gravity of 3.2. Sillimanite is the state mineral of Delaware (since March 24, 1977); SIllimanite is found near near Wilmington, Delaware. Sillimanite is found in Brazil, New England (USA), and Europe; it is found in areas of high-grade metamorphic rock.
SMOKY QUARTZ
Smoky quartz is a type of brownish quartz that has a smoky look
SNOWFLAKE OBSIDIAN
Snowflake Obsidian (also called flowering obsidian) is a volcanic glass that is usually dark (black or brownish) with white "snowflakes". This glassy, lustrous mineral is found in lava flows, and obsidian stones can be massive. Obsidian is formed when viscous lava (from volcanos) cools rapidly. Most obsidian is 70 percent silica. Obsidian has a hardness of 5 and a specific gravity of 2.35.
SOAPSTONE
Soapstone (also called steatite) is a soft, easily-carved, fine-grained metamorphic rock that can be green, brown, or gray. This stone has a greasy, soapy feel to it, hence its name. Soapstone is found worldwide. It is carved into figurines, beads, seals, bowls, pipes, cookware, and other items - it has been used since ancient times. Chemically, soapstone is composed mostly of talc, hydrated magnesium silicate (Mg3Si4 O10(OH)2) plus other minerals. Soapstone has a hardness of 1-1.5 (extremely soft - it can be scratched with a fingernail) and a specific gravity of 2.2-2.8.
SODALITE
Sodalite is a dark blue mineral with streaks of white, gray, pink, or green. It is used for carvings and jewelry. Sodalite is one of the mineral components of lapis lazuli. Sodalite is sodium aluminum silicate chloride; its formula is Na4Al3(SiO4)3Cl. Sodalite has a hardness of 5.5 to 6 and a specific gravity of 2.1 - 2.3. Sodalite is found in Brazil, Canada, India, Italy, Namibia, United States, and Russia,
SPECTROLITE
Spectrolite is another name for Finnish Labradorite (a variety of plagioclase feldspar). It is a fairly abundant grayish mineral that has brilliant iridescent flashes of color (usually green, blue, orange, or red) after it is polished. The crystals are transparent to translucent. Spectrolite is usually cut with a flat surface in order to highlight the brilliant flashes of color. Spectrolite has a hardness of 6 to 6.5 and a specific gravity of 2.70.
SPESSARTINE GARNET
Spessartine garnet (also called Spessartite garnet) is a type of a garnet that is orange (it varies from reddish orange to brownish orange to yellowish orange). The chemical composition is Manganese Aluminum Silicate. Crystals vary from transparent to translucent. This relatively rare gem is found in Sri Lanka, Australia, Madagascar, Brazil, Sweden, Myanmar, and the U.S. Spessartine garnet has a hardness of 7.0 - 7.5, a specific gravity of 4.19 (relatively heavy), and a refractive index of 1.8.
SPHENE
Sphene (sometimes called titanite) is a mineral that comes in green, yellow, white, brown or black wedge-shaped crystals (sphene means wedge in Greek). Sphene is used only rarely as a gem (due to its relative softness). It's chemical formula is CaTiSiO5, Calcium Titanium Silicate. Sphene has a hardness of 5-5.5, a specific gravity of 3.3 - 3.6, and a white streak.
SPINEL
Spinel is a very hard semi-precious stone composed of octahedral crystals. Spinel ranges in color from red to black to yellow, frequently resembling rubies. Iron and chrome are components of spinel, giving it its color. Spinel belongs to the feldspar species and is found in in Burma, Sri Lanka and Thailand. Some varieties include: Balas ruby (red spinel), Almandine spinel (purple-red), Rubicelle (orange), Sapphire spinel (blue), Ghanospinel (blue), Chlorspinel (green). Spinel is also laboratory synthesized. Spinel has a hardness of 8, a specific gravity of 3.58-4.06, and a refractive index of 1.72.
SUGILITE
Sugilite is a medium to dark purple semi-precious gemstone (it can also range from pink to brown to black). It is usually opaque with a waxy luster (but can be translucent) and often has brown, pink and white inclusions, looking like a purple version of turquoise. It is usually polished and not faceted. Sugilite has a hardness of 5.5-6.5 and a specific gravity of 2.75 - 2.80. This stone is not enhanced - massive stones are often found. Sugilite is Potassium Sodium Lithium Iron Manganese Aluminum Silicate; its formula is KNa2Li3(Fe, Mn, Al)2Si12O30. This stone was named for Ken-ichi Sugi, the Japanese geologist who discovered it in 1944. It is found in Iwagi Island, Shikoku, Japan and Mont Saint-Hilaire, Quebec, Canada, but the largest deposits are in northern South Africa.
SUNSTONE
Sunstone is also called aventurine feldspar (a variety of oligoclase). This gemstone varies from golden to orange to red-brown, and can be transparent or translucent. Sunstone is metallic-looking due to sparkling red, orange or green crystalline inclusions (these are hematite or goethite crystals). Sunstone is found in Canada.
TANZANITE
Tanzanite (strontium-rich Calcium-aluminum silicate) is a valuable, transparent, blue-violet type of zoisite resembling sapphire. Tanzanite has a hardness of 6 and a specific gravity of 3.35. It is often heat treated in order to produce a deeper blue-violet color. This mineral was discovered in 1967 by Manuel d'Souza (an Indian tailor) southwest of Mt. Kilimanjaro in Tanzania, Africa. Tanzanite is one of December's birthstones.
TIGER'S EYE
Tiger's eye is a yellowish-brown to reddish-brown gemstone that has a silky luster. This gemstone has bands of yellow and brown; when viewed from the opposite direction, the colors are reversed. Tiger's eye is usually highly polished and set as a cabochon (or cut as a bead) to display the stone's chatoyancy (light reflected in thin bands within the stone). Tiger's eye is a type of chatoyant quartz with fibrous inclusions (especially crocidolite). This stone is sometimes heat treated. Tiger's eye has a hardness of 7.0. Most tiger's eye is mined in South Africa, but it is also found in Australia, Brazil, Burma (Myanmar), India, Namibia, Sri Lanka (Ceylon), and the USA. Green-grey varieties of this stones are called cat's-eye quartz. Blue-grey to bluish varieties are called hawk's-eye. Deep brown varieties of this stone are called bull's-eye or ox-eye.
TOURMALINATED QUARTZ
Tourmalinated quartz is a variety of transparent quartz that has needle-like inclusions of black to dark green tourmaline crystals. This beautiful stone is found worldwide. Tourmalinated quartz has a hardness of 7.0. This stone is not enhanced.
TRANSVAAL JADE
Transvaal jade is not jade; it is a green to gray massive variety of grossular garnet, calcium-aluminum silicate. It is found about 40 miles west of Pretoria, South Africa. Transvaal jade can be distinguished from jadeite or nephrite by its high refractive index. Grossular garnet has a refractive index of 1.72 to 1.73, a hardness of 6-7.5 and a specific gravity of 3.5 - 3.67.
TRAPICHE EMERALD
Trapiche emeralds are rare, valuable emeralds that have a black, six-rayed star within them, caused by black carbon impurities (the star is not an asterism ). These stones are usually cabochon cut to display the beautiful spoke-like star. These stones are only mined in Colombia, South America. Trapiche emeralds are sometimes called star emeralds (but the term star emerald can also refer to emeralds with an asterism ). Trapiche is a Spanish word for the spoked wheel that is used to grind sugar cane.
TURQUOISE
Turquoise is a non-translucent, porous semi-precious stone (it is a hydrated phosphate of copper and aluminum) that is usually cut as a cabochon. Turquoise was believed to have been first found in Turkey, hence its name (Turquie is the French word for Turkey). The oldest turquoise mines are located in Alimersai Mountain in Persia (Iran) and in the Sinai Peninsula in Egypt. Turquoise is found in desert regions worldwide. The finest turquoise is Persian (Iranian) turquoise; it is robin's egg blue and has no matrix (streaks of the mother stone from which they were found). North American turquoise is greener and has a matrix streaks. Over the years, oil from your skin is absorbed by the stone and it will change color slightly. Turquoise has a hardness of 6 and a specific gravity of 2.60-2.85. Turquoise is the national gemstone of Iran. Turquoise is one of December's birthstones.
UNAKITE
Unakite is an opaque mineral that is green with patches of red and pink. Unakite is a variety of granite that contains green epidote and pink feldspar (but lacks mica). It has a hardness of 6 to 7 and a specific gravity of 2.86 - 3.2. Unakite was named for the Unaka Mountains Mountains in Tennessee, USA. Unakite is found in the USA and Africa.
VABANITE
Vabanite is a type of brown-red jasper with yellow flecks that is found in California, USA.
VARISCITE
Variscite, AlPO4-2H2O, Hydrated Aluminum Phosphate, (also called Utahlite) is a relatively rare translucent pastel green to emerald green gemstone with blue or yellow overtones (it is similar to chrysocolla, chrysoprase and turquoise). Variscite is found in the USA (in Utah and Nevada), Germany, Brazil, and Australia (in Queensland). Variscite has a hardness of 4.0 - 5.0 and a specific gravity of 2.57. It is not enhanced.
VULCANITE
Vulcanite (also called ebonite) is a hard, moldable, polished dark colored (ranging from brown to black) early rubber. Vulcanite was produced by adding sulfur to vulcanized rubber. It was used for combs, ornaments, and buttons. It is not the same as gutta percha.
XALOSTOCITE
Xalostocite is a pink grossular garnet that is found in a matrix of white marble. Xalostocite is found in Xalostoc, Mexico.
XYLOID JASPER
Xyloid jasper is jasperized wood (petrified wood). It is wood that has fossilized - all the original chemicals have been replaced with minerals, making a stone-like replica of the original wood.
ZIRCON
Zircon (zircon silicate) is a lustrous gemstone that comes in colors ranging from golden brown to red to violet to blue. Pure zircon is colorless, but most zircon stones are brown. Zircon stones can be heat-treated to become blue or colorless; sometimes, heat-treated stones revert to their original color. Clear zircon is sometimes sold (intentionally or otherwise) as diamond. It has a hardness of 7.5 and a specific gravity of 3.90-4.71.
ZOISITE
Zoisite (Calcium-aluminum silicate) is a gray-green mineral that occurs in cracks of igneous rock. Zoisite has three known forms: anyolite (a green matrix containing rubies), tanzanite (transparent, blue-violet containing strontium), and thulite (opaque pink crystals containing manganese). Zoisite was named for the Slovenian mineral collector Baron Sigismund Zois von Edelstein, who financed the expedition that discovered Zoisite.