Hello bluelotus777,
This is a hard one and I don't think people want to answer it but here goes for what it is worth.
Testing should be 100% reliable but about 3 or so years ago it was found there was a problem for testing as fraudsters had been inserting small natural or round keshi pearls into oysters and culturing them. Once cultured and when tested via X-rays the pearls were believed to be totally natural because they were all nacre. I believe those strands or necklaces were very expensive, same as the cost of top quality true naturals. But I am sure the experts in the technology could answer it better than I.
It didn't worry me because I only deal with antique and vintage natural pearls so could not be taken in. But anyone buying new natural pearl necklaces were scared and I guess for good reason.
If they had been declared for what they were and priced accordingly they could in my opinion been a asset but as they were not disclosing it was fraud and the prices were way too high.
But on the whole in my opinion testing is almost fool proof and the industry is now aware of the fraud and it is looked for.
I plan on having some of the round Basra pearl necklaces we are restringing tested but will probably list them as soon as they are ready at a lower price. But when Basra pearls are off round, baroques and in many cases slight oval because of wear I really feel that I can list them with 100% accuracy as they scream Basra. I always give a total money back including postage guarantee on all of my naturals. I have sold several Basra pearl necklaces and am always on the search for them. I sold two to one Indian lady from Canada and she was very happy. She needed them to be very, very long to go with her Sari so I had to use 3 to 4 strands to get the length and because I always remove any pearl damaged or worn etc. I should think she will get them tested one day if she has not already but she wanted to buy from me because of the trust she had in me as she had bought many pieces of other jewellery from my eBay site.
I realise eBay scares many buyers but it is safe if you are careful and you can always get your money back from PayPal (via the seller) if one has been cheated.
I now do not sell privately because it gives the buyer and myself safety which I discovered is not always the case when an item is sold privately. Saying that if I have a good, longstanding relationship with a buyer then I probably would sell privately. An item on eBay must be what is stated for the buyer and for the seller, well we are protected from buyers who scam. Of course the seller should have a good name and above all not be a fly by nighter.
Dawn - Bodecia
http://www.ebay.com/sch/dawncee333/m.html
eBay Seller ID dawncee333 Natural pearl collector & seller. And all round pearl lover.