Onyx is a black and white gemstone from the Chalcedony family that includes the Agates, Bloodstones and Carnelians. The Onyx has a red and white variant called Sardonyx or Sard that is brownish red and white.
The Onyx occurs in a variety of colors but is most famous for the dramatic black color that forms such a great contrast against other stones and cameos for jewelry. The stone has a smooth, waxy luster and is opaque.
During the latter part of the Art Deco period, Onxy was used by jewellers, in the 1930’s, as one of a number of alternative materials in order to cut costs. The black stone was used to contrast against more expensive gems like diamonds, emeralds and other precious stones.
Onxy is frequently dyed and heated to maximise the intensity of its color. It has a hardness of 6.5 ti 7 on the Mohs scale
It is a member of the chalcedony family which also includes carnelian, agate, bloodstone, etc. Occuring naturally in a variety of colors, black onyx is polished to enhance appearance, a member of the quartz family.
Onyx is a form of chalcedony, part of the quartz group. Like the other stones in the chalcedony family, onyx has a smooth, waxy luster. Onyx can be found in a wide range of colors, often layered.
Onyx is mined in Algeria, Arizona and Mexico.