They are most definitely dyed freshwater pearls. If purchased from eBay, I would have concerns that the clasp might not be as marked. There are a ton of fake "real" Tahitians all over eBay. To get a great idea of what real Tahitians look like, there is a thread showing IRL photos of Tahitians. Once you become familiar with the characteristics and colors these amazing pearls, it will be very easy for you to spot dyed freshwaters in comparison. And if you are ever in doubt prior to a purchase, just ask! This group is a most helpful bunch! Good luck in your search.