What is Onyx?

Onyx is a variety of the Chalcedony quartz. It consists of bands which are usually brown and white or black and white.

Onyx is formed when silica is deposited in gas cavities in lavas.

The name Onyx is derived from the Greek for fingernail as it is weak and transparent in its natural state.


Onyx is known to have been in use since Ancient Egyptian times.


Onyx can usually be cleaned in a steamer or ultrasonic cleaner, but the colour of chalcedony can sometimes change in extreme heat. Acids should be avoided and it should be stored away from other jewellery.

It is best to clean Onyx in warm, sudsy water, then rinse with clear water, wipe dry and leave to dry on a towel.

Caring for Onyx (Summary)

•    Store away from other jewellery
•    Clean in warm, soapy water
•    Rinse with clear water and leave on towel to dry


Onyx measures 7 on the Mohs hardness scale.