There are several material for the art of cameos carving, the most used are the shells, in particular they are the Cassis Madagascariensis (Sardonyx), theCassis Rufa (Cornelian), and the Strombus Giga (Pink Shell). Other materials used to carve cameos are hard stones as Agate (in several colors), coral, turquoise etc.
Sardonyx Shell (Cassis Madagascarensis)
Cassis Madagascariensis: ca 12 inches. Chestnut brown at bottom, and perfectly white on the surface for engraving.
Cornelian Shell (Cypraeacassis Rufa)
Cassis Rufa: ca 6 inches. Has an interior reddish layer; the exterior for engraving is pale flesh-coloured.
Pink Shell (Strombus Giga)
Strombus Gigas: ca 11 inches. Its white and pink layers are not always perfectly distinct from each other; also used for necklaces and buttons, fished in the Bahamas