This is a Koroit Boulder Opal from the Koroit Opal fields of Queensland, Australia. The stone is oval in shape and has been drilled. A bail could be fitted, at a small extra cost, so that it may be used as a pendant. It shows Green Opal and Purple Fire set in Brown ironstone.
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.