Our glossy black onyx beads will give your designs enigmatic shine. Onyx Onyx is a variety of chalcedony that is similar to agate, with straight rather than curved bands. Nearly all black onyx on the market has been rendered a uniform, permanent black color with a treatment by sugar and acid or heat. This process has been used on onyx for thousands of years and does not decrease the value of the stone. Mined in Brazil, India and Madagascar, onyx is said to enhance steadfastness and determination while setting one's mind to a task. Shop for beads in beautiful shapes like nuggets, hexagons and more!