Freshwater pearls come from oysters that mature in non-saline water (from lakes or ponds, as opposed to saltwater from the sea). Freshwater pearls usually are not as round as saltwater pearls and therefore less expensive. Also freshwater mussels are larger and can thus produce more pearls at a time than saltwater oysters. As a result, freshwater pearls are more abundant and that is another reason why they are less expensive.  Although most freshwater pearl information lists several areas of the world (for example USA and Japan) as home to pearl-producing mussels, the global freshwater market is overwhelmingly dominated by Chinese pearl farms, which account for nearly all freshwater pearls sold today.