Onyx is a natural gemstone, if exposed to sudden changes of temperature or knocked it can be brittle. The safest recommendation therefore is to avoid ultrasonic or steam cleaning and simply use hand warm water and a bit of soap. Wash gently with a soft cloth or toothbrush and pat dry after.
: Onyx has traditionally been one of the most important engraving and cameo gemstones. : Onyx comes from the Greek word meaning fingernail , from a legend involving Cupid clipping Venus' fingernails! : Black Onyx is believed to be a potent protective stone. : Onyx is formed by the deposition of silica in gas cavities in lava, which results in distinctive bands we can see.