From the Greek "onyx," meaning "nail." In myth, Cupid trimmed Aphrodite's nails, and the clippings turned to stone.

A variety of chalcedony. Most commonly seen as solid black, though true onyx carries black and white banding. Since Roman times, that banding has been carved in relief to produce cameos—the natural contrast between layers used directly as light and shadow. The structure of the stone became the medium of expression.

Found in Brazil, India, and Uruguay. One of very few stones used without interruption from antiquity to the present.