Question: what is the difference between freshwater pearls and saltwater pearls?
Answer: Saltwater pearls have a thinner nacre coating, ranging from 0.5mm to 6mm. Freshwater pearls, on the other hand, are made almost entirely of nacre. The reason for this difference is that the core piece (the one around which the nacre forms) inserted in freshwater pearls is a lot smaller than that put in saltwater ones.