A mysterious gleam of black will accent your designs when you use the onyx 8x10mm tumble nugget beads from Dakota Stones. Available by the strand, these beads feature a tumbled nugget shape giving them an organic feel. 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 set one's mind to a task. Add these glossy beads to designs with bright colors for a daring contrast.