We buy opal rough.
Play-of-colour where present; body tone runs black through white to transparent.
Send photographs of what you have Tell us the weight and where it is from. There is no obligation.How to tell if this is what you have
No crystal habit — nodules, seams and infillings.
amorphous
Play-of-colour where present; body tone runs black through white to transparent.
What it gets mistaken for
Opal is commonly confused with doublets and triplets, synthetic opal and opalite glass. That cuts both ways — people sell it as something less than it is at least as often as the reverse. If you are not certain what you have, send photographs anyway and say you are not sure. We would far rather look at something and tell you it is not what you hoped than have you throw it back on the heap.
Also traded as: black opal, boulder opal, crystal opal, fire opal.
Where it comes from
We buy opal from Australia, Ethiopia, Mexico, Brazil, Indonesia — and from anywhere else it turns up. A locality we have not listed is an omission, not a refusal.
Treatment
Smoke and sugar treatment of Ethiopian material; doublets and triplets are assembled and excluded as composites.
Tell us what has been done to it, if you know. We buy treated material where the treatment is a normal part of the trade — what we cannot do is find out afterwards, because then it is a problem for whoever owns the stone next and eventually that is us.
How to photograph it
Ethiopian hydrophane opal absorbs water and CHANGES APPEARANCE while it is wet, so the wet-and-dry advice we give for everything else actively misleads on this one species. Photograph opal dry, in daylight, and tell us if it has been wet recently. The desk knew this and the page did not say it.
Daylight, on a plain white surface, and wet and dry both. Rough seen dry is frosted and reads far paler and greyer than the same stone wet — a parcel photographed dry has cost its owner money more times than we can count. Put a coin or a ruler in the frame for scale. The full guide is here.
Send photographs of what you have Tell us the weight and where it is from. There is no obligation.