This is a round Coober Pedy opal, approximately the size of a 5 pence piece. It has a diameter of 1.8cm, is ca. 3mm thick with a slightly curved surface and weighs 8.5 carat. The colours are typical for Coober Pedy with lots of tightly packed red and green pin-prick fire. The back is flat and slightly chipped on one edge (see photo, 12 o’clock). I could have taken the chip out but would have lost some of the circumference. It will not be visible from the top once the stone is set, and if required, you can always file if off.