This is a shaped and polished, ready to mount or display, natural Lightning Ridge opal from the mines of Australia.
It is an oval shape, domed and polished on one side and is 11mm high, 7mm wide, 2mm thick and of 1.55 carats.
This opal has a dark grey background colour, and bright flashes of mainly red, with some orange, green, yellow and blue across its entire surface. the reverse of the stone has a small channel where potch/sand has been removed, but it does not effect the front surface.
A totally unique stone, which would make an unusual ring/pendant or simply kept as a mineral sample.