Yes, they assured me it was real and I paid 30€, which is almost 40 USD
You're not going to get any real opal for $40.00 U.S. It's just a shaving, which is then attached to plastic. While it may be a silver of "real opal," it's more likely plastic. I'm afraid they weren't honest with you. This is definitely a doublet. Real Opals (U.S. money) run $200 and up, and for any quality opal ring or item, you're probably talking over $500. I would take this to a quality jeweler who does appraisals if you'd like to be sure, and then perhaps get your money back. But it doesn't look like a genuine opal. I'm pretty sure any reputable jeweler will be honest with you and let you know this is imitation. I'm sorry this happened to you, but typically when things sound too good to be true, they generally. Genuine opals, unless they are poor quality, aren't cheap. And genuine opals with a lot of blue in them (not milky) can run into the $1,000 range. There is no way you can purchase a genuine opal with a lot of blue in it for $40.00. Unfortunately, this one doesn't even look real. I'd take it in and then if you're not happy, I'd get in writing what it's made out of and try and get your money back. I hate to say it, but this doesn't even look like a real opal doublet. They can run into the $200.00 range and are usually thinner and very flat on the surface.
I think this is probably an opal triplet.
Here's a little article:
"Triplets
Triplets consist of three layers:
1.A black backing as above
2.A paper-thin slice of opal in the middle
3.A clear glass, quartz, or plastic capping in the shape of a dome. The slice of opal in a triplet is usually extremely thin (paper-thin) so the clear capping serves to give the stone a nice cabochon on top. The clear capping may also magnify the colour of the opal slightly, and also serve to protect the opal.
Because triplet opals have a clear non-opal capping on top, it is easy for an experienced person to identify a triplet immediately by the appearance of the stone. Triplets usually have a 'glassy' appearance and the light reflects differently from the top of the stone. You can look at the side of the stone to identify a straight line where all the layers meet, and also look at the back of the stone. If the back of the stone appears to be black plastic then you are not looking at a solid stone. Be aware however that it is also very common for a backing to be made of black potch (exactly the same stone which forms the backing of a natural black opal) or brown ironstone (which is also the natural backing for Queensland boulder opals).
Triplets are normally cheaper than doublets because they contain less real opal. Because the top of the stone can be made from synthetic material, triplets can be a lot more resistant to impact than solid or doublet opal stones. (Opal by its nature is a fragile gemstone)."
Here's some pictures of opal triplets - as you can see, they look a lot like your stone. They run $10 to $20 at auction.
http://www.opalauctions.com/auctions/triplets/
