Sardonyx and Onyx

Sardonyx and onyx are layered stones. They are often used in the art of gem carving and engraving, also known as glyptography. The geode is usually cut from agates or chalcedonies with even parallel layers, a lighter layer above a darker layer.

Sardonyx has a brwon base with upper layer being white in colour.
Nature onyx is a combination of a black or blackish-brown base and a white upper layer.

Treatments

Black onyx does not exist in nature and should not be confused with onyx, it is actually dyed black agate. Agate is soaked in a sugary solution and then heated in sulfuric acid to carbonize the sugar to obtain the black colour.

Caring

Aquamarine jewellery should be kept in a dark place. If it left out in the sun for too long, it will become paler in colour.

Clean with warm, soapy water and soft bristle brush.