This is Black Opal Potch and comes from Lightning Ridge, New South Wales, Australia. It is very unusual as it has colour in it, Blue, Green and Purple. Potch is normally classed as colourless Opal and comes in White, Black and in this case, Grey.
If you see an opal on this website that you might like to have as a pendant, please contact Peter to discuss if it is possible with that particular stone.
You also need to state if you wish to have a bail fitted or not. If you do, then you would need to be charged for the cost of metal, silver or gold.