Obsidian Stretch Bracelet - 6mm GemstoneObsidian is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly. Black Obsidian is a deep saturated black with a very polished surface. We use 6mm AAA Quality beads and professional grade elastic for a sturdy stretch to fit all wrist sizes. These bracelets look great stacked together with each other or with any number of other gemstone bracelets in the collection. Black goes with everything, so you can really