History The name "onyx" comes from the Greek word for "fingernail," referring to the translucence of the white-colored layer of this multi-layered stone. According to myth, Cupid trimmed the nails of the sleeping goddess Venus. The Fates turned those clippings into stone to prevent even a part of Venus from dying. The Romans were experts at glyptography (the carving of layered stones to reveal different colors) and crafted beautiful seals from onyx (white layer over black base) and sardonyx (white layer over reddish-brown base). The patterns were cut in negative relief. Engravings with a negative picture are called intaglios and those with raised image are cameos. In the Middle East, onyx was associated with sorcerers. While ruby is the birthstone for July, black onyx is an alternative stone for the month and is associated with the Babylonian Zodiac sign of Capricorn. Metaphysical Properties Black has been associated with regeneration and new beginnings. Black onyx is thought by some to have protective qualities, making it advantageous to carry when traveling. It is said to be useful in fighting basic fears and helping to move beyond bad relationships--as well as to heal old emotional wounds. The Romans associated onyx with courage and it is thought to be useful when one is defending him/herself against unfair criticism. Geological Properties Onyx is a form of chalcedony, which is a microcrystalline quartz formed in the gas cavities of lava. Its multi-layered structure is similar to that of agates. When the stone has a black base and a white upper layer, it's called onyx. (Black onyx is uniformly black chalcedony.) When the base is brown, it is called sardonyx while carnelian-onyx has a red base. Much of what is referred to as "black onyx" is gray chalcedony that has been chemically treated to be a rich black. The gray stone can be saturated with a solution of cobalt chlorate and chlorammonium, or it can be immersed for a prolonged period in a sugar solution and then heated in sulphuric acid to carbonize the sugar. Brazil supplies the best multicolored raw material, but onyx is found worldwide. Gray chalcedony is found in India and China.