Obsidian is a volcanic glassy rock that is usually found in black but also in brown or gray. Its hardness is 5.5 and its specific gravity is 2.6. It has been known since antiquity since it was used to make sharp objects, weapons, etc. In modern medicine it is used to create extremely fine and sharp scalpel blades.
All minerals used for the creation of our kombolois are mostly gemstones used to craft jewelry. Please treat your komboloi with care. Inclusions, cracks and breakage surfaces are a natural phenomenon and should never be associated with wear and tear.