Bead, rainbow obsidian (natural), 18mm round, B grade, Mohs hardness 5 to 5-1/2. Sold per 8-inch strand, approximately 10 beads. - Fire Mountain Gems and Beads
Amazon.com: 8mm Natural Black Obsidian Beads Round Gemstone Loose Beads for Jewelry Making (45-48pcs/strand)
Okoro" 10mm Matte Black Obsidian Natural Beaded Bracelet - BOYBEADS New York
Golden Sheen Obsidian | Golden Sheen Obsidian Beads | Pinecone Beads