Onyx and Sardoynx are both types of Chalcedony.  Both stones are banded which means they have parallel lines running through them.  Onyx comes in black or white, while Sardonyx is usually dark brown, orange brown, or brownish red. 

Since the Ancient Greeks, Onyx and Sardonyx are extremely popular for cameo brooches, beads, and tablets. 

Sources: Brazil, USA, Madagascar. 

Hardness: 6.5-7 on Mohs scale. 

Toughness: Good.  

Sardonyx is an alternative birthstone for August. 

Brereton's have a selection of vintage and antique Onyx and Sardonyx jewellery.   Please contact us at webenquiries@brereton.ie for more information.