Bold shape and dark color combine in the Dakota Stones matte onyx 30x40mm rectangle beads. Available in 8-inch strands, these beads feature a beautiful black color and a stylish matte finish. These beads feature a large rectangular shape with rounded edges. This material has been rendered a uniform and permanent black color with a treatment of sugar and acid. This process has been used on the gemstone for thousands of years and is water safe. These beads are polished and then tumbled to achieve the matte finish. Mined in Brazil, India and Madagascar, onyx is said to enhance steadfastness and determination, setting one's mind to a task. These large beads would make excellent backdrops for smaller, brighter beads.