This is a shaped and polished, ready to mount or display, natural Lightning Ridge opal from the mines of Australia.
It is a freeform shape, domed and polished on one side and is 13mm high, 7mm wide, 2.50mm thick and of 1.60 carats.
It has a grey background colour, with bright flashes of red, pink, green, yellow and blue across its entire surface. There is a little patch of sand/potch on the reverse, but it does not effect the front surface or its value.
A totally unique stone, which would make an unusual ring/pendant or simply kept as a mineral sample.