As consumer we have to do our homework and pay attention to details. I think "cultured pearls" are the key words. Genuine cultured pearls are described as such for other items, for example from the links below:
You can search the word "pearls" on their website, and sort pricing from low to high. You'll be able to see many "Tahitian" pearl items are very pricey. That may alert you to something that you may have missed.
purveyor of pearls
Senior Pearl-Guide.com Pearl Expert
I agree with Amanda...customers should not have to deconstruct an advert or listing word by word. Most people looking at that would not have a clue that they were fakes, they would think, oh those are nice, I wonder why some tahtians are so much more expensive, those sellers must be rip off merchants '