Obsidian is volcanic glass — lava quenched too fast to crystallize — prized since the Stone Age for edges sharper than surgical steel and today for its deep, mirror-black polish and varieties from sheen to rainbow. Hardness 5–5.5.When obsidian is in stock at GEMIC Institute it is natural, certified by our laboratory and photographed exactly as offered. Ask about current pieces — see also our snowflake and starry night obsidian collections.