General

Onyx: An August Birthstone

Onyx August BirthstoneThe name Onyx originates in Latin (same spelling) from the Greek word for claw or fingernail.  Onyx is a banded variety of chalcedony, a cryptocrystalline form of silica minerals.  The bands may alternate colors, and they run parallel to one another, different from agates.  Black Onyx is one of the most famous varieties, and artificial treatments have been used since ancient times to produce the color.  Much of the black onyx on the market is artificially colored, and some is actually stained agate.