The art of glyptics, or carving on colored precious stones, is probably one of the oldest known to humanity. Intaglios, gems with an incised design, were made as early as the fourth and third millennia BC in Mesopotamia and Aegean Islands. They display a virtuosity of execution that suggests an old and stable tradition rooted in the earliest centuries. The tools required for carving gems were simple: a wheel with a belt-drive and a set of drills. Abrasives were necessary since the minerals used were too hard for a metal edge. A special difficulty of engraving intaglios, aside from their miniature size, was that the master had to work with a mirror image in mind. Apart from their artistic value as ornamentation, intaglios were given by emperors to members of their court as marks of royal favor. To wear such a gift was not only a sign of honor, but also of loyalty. The very fine portrait on this intaglio bears a close resemblance to Constans, son of Constantine the Great and joint emperor (337 - 350). The profile shows a handsome young man wearing either a diadem or a tight fitting cap, with his toga pulled up tightly around his neck. His expression is vivid and animated, revealing a confident young man who might have given this intaglio as a token of trust to a worthy friend.