Judging quality
The sheen only appears along one plane, so the cutter's orientation makes or ruins the piece. Rotate it under a single strong light: real rainbow obsidian shows nested rings, not a surface film.
Volcanic glass
Rainbow Obsidian
Black obsidian containing aligned nanoscale magnetite crystals that throw concentric bands of green, gold and violet when the stone is oriented and polished correctly.
Care
Glass; scratches show badly on the polished face.
History & lore
Mexican rainbow obsidian from Jalisco has been carved since the pre-Columbian era — Aztec mirrors of obsidian were polished from exactly this material.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Rainbow Obsidian
- What is Rainbow Obsidian?
- Black obsidian containing aligned nanoscale magnetite crystals that throw concentric bands of green, gold and violet when the stone is oriented and polished correctly.
- How hard is Rainbow Obsidian and what is it made of?
- Rainbow Obsidian is a Volcanic glass-family mineral with the composition SiO2-rich glass with nanoparticles. It crystallizes in the amorphous system and rates 5-5.5 on the Mohs hardness scale. It occurs in black, iridescent, emerald green, purple.
- Where does Rainbow Obsidian come from?
- Notable localities for Rainbow Obsidian include Jalisco, Mexico, Oregon, USA.
- How do you tell good Rainbow Obsidian from filler?
- The sheen only appears along one plane, so the cutter's orientation makes or ruins the piece. Rotate it under a single strong light: real rainbow obsidian shows nested rings, not a surface film.
- How do you care for Rainbow Obsidian?
- Glass; scratches show badly on the polished face.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.