In jewellery design, as in fashion, colours look crisper against a background of black. In fine jewellery, the black backdrop is often supplied by onyx, a chalcedony quartz with a fine texture. Some onyx also displays white bands or ribbons against a black background. If the layers are even, this type of onyx can be carved into cameos.
Onyx was very popular with the ancient Greeks and Romans. The name comes from the Greek word onux, which means finger nail. The story is that one day Cupid cut the divine finger nails of Venus with an arrow-head while she was sleeping. He left the clippings scattered on the sand and it was turned into stone so that no part of the heavenly body would ever perish.

Onyx which is reddish brown and white is known as sardonyx. Sardonyx was highly valued in Rome, especially for seals, because it was said to never stick to the wax. Roman General Publius Cornelius Scipio was known for wearing lots of sardonyx.
Black onyx especially shines when used a backdrop for colour play. Its fine texture also makes it ideal for carving, making it a favoured material for today's lapidary artists. Onyx was often used as the perfect foil for carved rock crystal or the drop dead red of rubies in art-deco designs. It is also popular in marcasite jewelry. So if you like to add a little black magic to your jewelry design, consider onyx.