Freshwater pearls are produced by mussels and oysters that live in rivers, lakes or ponds. The majority of available freshwater pearls are 
cultivated; high quality natural specimens are rare and almost non-existent.
The widest variety of pearl shapes and colors are produced in freshwater pearl cultivation using mussels. This was begun experimentally in Japan in the 1920s and 30s, and became an industry during the 1960′s to early 1980′s, albeit on a smaller scale than ocean (Akoya) pearls.
Mussels grow to sizes more than 10 times as large as akoya pearl “oysters” and can therefore be used to cultivate pearls reaching South Sea pearl sizes. Most are cultivated without any shell bead nucleus, yet can grow to rival
the size of the largest bead-nucleated Akoya pearls. This can be done with far less advanced surgical skills than ocean pearl cultivation; it became widespread in China in the space of a few years, while success with ocean pearl cultivation required decades.
Shapes of freshwater pearls without nucleus are largely left to chance. Depending on their position and the length of time they are left in the mussels, they will tend to be either oval-drop-barrel or lentil-button-flat. Colors include some whitish, but most are in the peach-pink-lavender range with occasional flecks of gold or brown-green pond slime color.
Flat shell nuclei are used to cultivate coin pearls, and round shell beads are also used in freshwater pearl cultivation, but to date rounder pearls can be made without nucleus than with. Mussels produce nacre at a more rapid rate than ocean pearl “oysters” leading to extravagantly baroque pearls that are only available in freshwater.
China has dominated the freshwater pearl industry since the 1970s, and the fierce competition there has led to prices ranging from incredibly cheap to reasonable, along with constant innovation to create new and different varieties.
A note about Japanese freshwater pearls:
Freshwater pearl cultivation originated in Lake Biwa, Japan in 1914. For over half a century, pearls from this lake enjoyed status as the most beautiful in the world. Consequently, freshwater pearls from all over Asia began to be falsely referred to as “Biwa Pearls.” (Technically, Biwa pearls can only be from Lake Biwa.)
Sadly, around the mid-1970s, pearl production in Lake Biwa began to decline then nearly ceased to exist. The primary cause was environmental pollution. Today, measures are being taken to reinvigorate pearl production there. Meanwhile, Lake Kasumi ga Ura has emerged as one of Japan’s only freshwater pearl producing bodies of water. Please refer to our description of Japan Kasumi pearls for more information about their unique origin and the fascinating history and dedication of their farmers.
For information on American freshwater pearls please contact Gina Latendresse of the American Pearl Company: 1-800-455-6602. Her family has been in the business of farming and selling American freshwater pearls since 1954. Please do not be fooled by other suppliers claiming to be selling American Pearls, especially online.
The Making of Freshwater Cultured Pearls
Traditional pearl cultivation involves first inserting a bead nucleus, then a piece of mantle tissue, inside a mollusk. Not long after this method began, pearl farmers discovered, quite accidentally, that nacre (NAY-ker) could form around mantle tissue without the presence 
of a bead nucleus. Leaving out the bead nucleus made the process easier and soon, this became an accepted means of production. Most freshwater pearls are nucleated only with a small piece of mantle tissue, although great strides have been made in recent years to produce bead-nucleated freshwater pearls.
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