Cameo is a small relief carved on a gemstone or shell. It features a raised image, often a portrait, cut in the light-colored layer, and the dark shade left as the background. For centuries, cameos have been featured in jewelry, vases, dishes and military accessories (such as helmets and sword handles). The art originated in Asia as a decoration on the reverse side of seals. It was perfected by the ancient Romans and enjoyed a great revival in Victorian times.
Hard-stone cameos are carved from opaque gem material (such as onyx or agate). They are more durable and more expensive than shell cameos.
Because of its durability and natural multi-colored layers, agate is the most popular gemstone used for carving cameos.
Traditionally, cameos carved from shell have been more informal and affordable than gemstone cameos. Conch shells provide the material for the cameo cutters of Torre del Greco, Italy – the main manufacturing city for shell cameos.
Carnelian shells are the most popular material used in cameo carving. Their brownish, peach or orange colors offer sufficient contrast between lighter foreground and darker background.
The sardonyx shell has a thick outer wall and a brown interior, yielding highly valued marble-like cameos with light-colored reliefs against dark backgrounds.
Cameos carved in mother-of-pearl exhibit an opalescent, bluish-gray color and look especially beautiful when set in silver.