Sorry to hear these pearls are not cultured pearls as you had thought!! If only you could have found us earlier!
How did you finally discover they were imitation pearls? It will help other visitors facing the same problem. Fake pearls are flooding the market. Not that there is anything wrong with faux pearls. Coco Chanel, adored wearing imitation pearls; it's just annoying when the true nature of these types of pearls, are not declared at point of sale.
If Pearls look to good to be true, they probably are! The best-of-the best imitation pearls are the Majorica pearls.
It can be very hard to tell the difference between Cultured pearls and the well-made glass and plastic imitation pearls, even with a trained eye. This is one of the reasons I created this web-site about Antique jewelry and Pearls.