Check the listing for details. rainbow obsidian rough Lot. Condition: New. Listed at 54.00 USD. The product is a pieces of rainbow obsidian rough, a type of lapidary material that is commonly used for creating polished stones or jewelry. Obsidian is a naturally occurring volcanic glass, known for its iridescent quality and unique colors. This rough piece would be ideal for collectors or hobbyists looking to work with stones or minerals in their lapidary projects.