This is an Opal Doublet from Coober Pedy in South Australia with the backing coming from the Koroit Opal fields of Queensland, Australia. It has a body tone of N2, which classes it as a Black Opal and a Brightness rating 4. The stone is dark Blue in colour, however as you move it in the light, you get flashes of Light Blue and Green.This would make a lovely pendant in the right setting.
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.