Black Opal is a greenish type of opal with black mottling and gold flecks. Usually found in ancient hot springs, the gem is usually tumbled smooth and cut cabochon. The phrase in the North "Black as a black opal" means, effectively, not very black (or evil) at all, and is used to describe good-hearted rogues and similar individuals who would be embarrassed by praise. A typical specimen has a base value of 1000gp.
Black Opal - Black opal is characterised by a dark body tone causing brightness of colour which is unmatched by lighter opals. Black Opals are usually mined in Lightning Ridge, New South Wales, and are the most famous, and sought-after type of opal. The term 'black opal' does not mean that the stone is completely black (a common mistake), it simply means the stone has a dark body tone in comparison to a white opal