Black onyx 7mm ball Fujiun stone finishA must see for those who feel that the classic black onyx is not enough! A must see for those who feel that the classic black onyx is not enough! We would like to introduce a bracelet made of the classic black onyx and Fujiunseki (light amethyst). 1. Introduction to Black Onyx Black onyx, like agate, refers to a collection of small quartz crystals. Originally it meant striped agate (sardonyx), but in recent years it seems to be mainly called black