The first demantoid garnet (a type of andradite) was discovered in the Urals in the mid 19th century. Russian miners were immediately struck by the highly refractive nature of the gem and its exceptional fire and gave it a name that compared its flashing green colour to the eyes of a demon.
This relatively large stone with its distinctive ‘horsetail’ inclusions caused by the presence of fine asbestos fibres (unique to demantoid garnets) is mounted in a bow and swag diamond brooch c.1890, which makes it highly likely that it is in the original setting. The estimate is £3000-4000 at Matthew Barton of Olympia Auctions on November 20.