Emerald

Emerald, the precious form of beryl (q.v.), having a fine green colour. As a gem it ranks after the sapphire and diamond in value. It has been successfully imitated in paste, the natural colouring matter, chromium-sesquioxide, being employed. The finest specimens come from Muzo, in New Granada, where they occur in a fossiliferous limestone. The oriental emerald is the very rare green variety of the sapphire.