Hypnotizing style fills the Dakota Stones sardonyx 10x20mm rice beads. Available in 8-inch strands, these beads feature thick and thin white stripes against a black background. These beads are almond-shaped, which gives them an elegant appearance. Sardonyx is an onyx that is characterized by parallel lines of sard and different colored minerals. It is a distinct and dramatically banded variety of chalcedony composed of quartz layers. Sardonyx is believed to improve memory and increase one's analytical talents. Sardonyx is mined all over the globe and is also known as tuxedo agate. Use these beads to make a stylish necklace even more sophisticated.