Semi-Precious - Black Onyx Round Beads Most Black Onyx beads are artificially dyed to enhance the black colour of the gemstone. Onyx is a member of the chalcedony family which is a form of Quartz and in its natural state comes in a large range of colours that give a natural banding effect through the stone. It can be found in a number of places around the world but the largest supply of jewellery grade black onyx comes from Brazil.