The Dog Argus; engraved Cornelian

Odysseus, dressed characteristically in a sailor's conical hat, short shirt, and small cloak, carries a beggar's staff, on which he leans in a meditative way, watching the dog.

The dog comes out of a sort of tower. It is not a kennel, rather the palace of Odysseus represented in a shorthand way by the gem-engraver, who had no room to make it larger.

Cornelian
Cornelian is a red variety of chalcedony which is cryptocrystalline quartz. Its red colour is due to the presence of iron impurities in the form of iron oxide or hematite. It can vary from a flesh red to a clear red. It is usually cut en cabochon, or into beads, and is also used for intaglios and cameos. Imitations of cornelian are made by the staining of agate.
Sources
Originally found in the deserts of Arabia and Egypt, it has also been found in the Rio Grande area, India, China, Colombia, Saxony, Scotland, West Germany and USA.