Onyx - Black Cryptocrystalline Quartz

Black onyx is commonly used for both men's and women's jewelry. Onyx contrasts well with gold settings that give it a bold appearance. In Victorian times, onyx was popular as mourning jewelry and black onyx provided a dramatic contrast in silver set Art Deco jewelry. Onyx is black (or white banded) agate (cryptocrystalline or chalcedony quartz). It should not to be confused with onyx marble, which is limestone.  Some varieties of onyx differ in color. Synthetic materials such as black, opaque, devitrified glass as well as black opaque cubic zirconia have been used as onyx substitutes. Natural gemstones such as augite and opaque, black spinel have also been offered or misidentified as onyxes.