Onyx is a form of quartz. Pure black onyx is common and the most famous variety, although onyx can be found in almost every color. Onyx is not meant to be cleaned with an ultrasonic cleaner or any type of abrasive or ammonia based cleaner. Doing so can cause discoloration of the stone.
In jewelry, black onyx is a very common stone used to make pendants, rings, bracelets, and earrings. Black onyx jewelry is often in great demand due to the common hue of the stone and the ability to adapt to the wardrobe.
