Onyx, a chalcedony quartz, was a favorite stone with the ancient Greeks and the name comes from the Greek word "onux," which means fingernail. In Greek mythology onyx was formed when Eros clipped the goddess Venus' fingernails while she was sleeping and scattered them on the beaches of the Earth. The Fates turned the fingernails to stone so that no part of the heavenly body would ever perish.

Onyx is the alternate birthstone for February and the Mystical birthstone for the month of December.