Freshwater Pearls - Uniquely Different

You probably already know that both freshwater and saltwater mollusks can produce pearls,and that saltwater mollusks that produce cultured pearls are called oysters (they look more like a scallop than the edible oyster), and the mollusks used to culture freshwater pearls are called mussels.

Probably the most significant difference, between culturing saltwater oysters and freshwater mussels, is that one freshwater mussel can accept up to 50 of the implants used to produce pearls and from those 50 implants, up to 40 pearls can successfully be harvested.

The smaller akoya oyster can accept up to five implants, and the larger Tahitian and South Sea pearls can accept only one implant per oyster. The akoya oyster can produce up to 5 pearls and Tahitian and South Sea of course can produce only one pearl from the single implant. The time until harvest for the freshwater pearl can be anywhere from 2 to 6 years. The period for the saltwater oyster to produce a pearl is only 6 months to 26 months.

Freshwater mussels are implanted with a piece of mantle tissue,the thin membrane lining the mollusks shell. But saltwater implants also include a bead made from the shell of a freshwater mussel. Implanting is different between the saltwater and freshwater mollusks in that the saltwater implant is done in the animals gonad, while the freshwater implantation is done in the mantle tissue next to the shell.

The pearls themselves are different, in the freshwater pearl the pearl is usually solid nacre, and the saltwater pearl it is usually only at most 3 mm, because of the bead implant.

The different techniques are the reason why freshwater pearls are rare if they are spherical, and of course the saltwater start with a round implant and the nacre is built up on that. About 2% of the freshwater pearl harvest is round, while up to 80% of the saltwater harvest is round.

By Patrick Cavanaugh