Biwa pearls, also known as freshwater pearls, are a type of pearl that is produced by freshwater mussels rather than saltwater oysters. These pearls are named after Lake Biwa, which is located in Japan and was historically a significant source of freshwater pearls. However, the term "Biwa pearls" has become more generalized and is used to refer to freshwater pearls produced by mussels in various freshwater bodies, not just Lake Biwa.
Freshwater pearls are formed when a foreign object, such as a grain of sand or a piece of tissue, gets trapped inside a mussel's soft tissue. In response, the mussel coats the irritant with layers of nacre, a crystalline substance that gives pearls their lustrous appearance. The growth process of freshwater pearls is slower than that of saltwater pearls, which often results in unique shapes, sizes, and colors.
Because they are produced in freshwater environments, freshwater pearls can come in a wide range of colors, including white, pink, lavender, and various shades of pastels. They can also be irregularly shaped, baroque, or more symmetrical, depending on the conditions under which they formed.
Freshwater pearls are often used in jewelry-making, and their availability and diverse appearances make them a popular choice for those seeking more affordable pearl options compared to the rarer and generally more expensive saltwater pearls.