Main index --- Minerals list --- Silicates index Sard
Derivation:From Sardis in Lydia (Greek)
Description: Light or dark brown chalcedony.
If chalcedony is brown, then it is a sard. If it is more orange or red, then it is a cornelian, but one grades into the other. It seems that sard is the older name, and was used for the complete range of colour, but now the redder stones are called cornelians.
Derivation:From "onyx" (Greek) nail or claw
Description: Striped chalcedony, particularly black and white.
Chalcedony is often striped. As different layers build up when the stone is formed, they are of different colours. If you cut across the layers, you get the striped effect. Black and white stripes are called onyx. They can be used for making cameos, where the jeweller cuts away at one layer of colour, down to a lower, different coloured, layer, to make a picture, such as a portrait, and its background.

Sardonyx Sardonyx
Description: Striped brown and white chalcedony.
If you have an onyx with brown and white stripes, then it becomes a sardonyx. These can be cut in several ways. You can have a cameo (see above), a slice through (which is sometimes called a banded agate), or, most striking of all, you can cut it so it looks rather like an eye (see right). These were used by Sumerians, Egyptians, Greeks and Romans to ward off evil.

Larger pictures of Sardonyx:

This natural specimen shows the bands of agate.
This is a cut and polished specimen.
It has been cut to show the layers so it looks like an eye.