natural gemstone 8 mm smooth round black onyx beads and 12 mm faceted clear quartz round beads silvertone metal 20 inch long necklace silver toggle clasp This lovely necklace features 8 millimeter faceted clear quartz beads and 12 millimeter black onyx faceted beads. It has silvertone links and closes with a silvertone toggle clasp. Check out my other listings for more lovely gemstone pieces.