This is a shaped and polished, ready to mount or display, natural Andamooka opal from the mines of Australia.
It is a freeform shape, polished on one side and is 26mm high, 13mm wide, 2.50mm thick and of 9.60 carats.
These opals are not of the quality from other areas in Australia and are often boiled in sugar to darken the background to enhance the colour plays. This natural opal has a pale grey background, with muted pin-fire green flashes across its entire surface.
Not a great stone, but would make an interesting pendant or kept as a large example of this type of opal.