Although I hope all the sellers on Ebay are honest, there are always some fraudulent pearl jewelry listings out there. If you see one or more of the following in the listings, those listings are most likely fraudulent and you want to stay away from them:

• If the seller is selling 'AAA' Akoya pearls from Japan at incredibly low prices, such as 7mm strands for $99, or 8mm Studs for $40 you can guarantee that’s too good to be true. It would be impossible for them to sell pearls as they described as farms in Japan charge more just to send them to a factory.
• Similar to above, Tahitian pearls for < $50 are also too good to be true.
• If the seller claims that the pearls are natural - they are not! Natural strands can cost hundreds of thousands of dollars! They are all cultured.
• Do not believe the certificates, appraisals, pictures. Unless someone is signing their name to a specific appraisal it is worthless. The appraisal must be for the specific piece as well, meaning the certificate should have a photo of that piece of jewelry along with its other information, e.g. weight.

Also, watch for the negative feedback. Pearl experts can see immediately if the seller is dishonest in their descriptions. Most consumers cannot. But if the seller is dishonest SOME consumers will know. Maybe you will see 1000 good feedback, and only 30 negative. READ the negative feedback, and see if it is consistent. Watch for things like (very low luster pearls, high blemishes, etc.)
Have fun bidding!