Natural freshwater pearls occur in mussels for the same reason ... their freshwater pearls are round enough and good enough to pass as Japanese akoya. China already sells round white pearls ...

He says that part of the reason the Marie Antoinette pearl is worth so much is because it's a natural pearl, which brings us to one quality that determines a pearl's value. Natural versus cultured.

Natural versus cultured ... Today, Mikimoto is widely considered the grandfather of cultured pearls. He used Akoya pearls, which are the traditional white round pearls you're probably familiar ...