are named after the Japanese word for poppy seeds. These small, asymmetrical bumpy Pearls have a high luster and are a natural byproduct of the cultured Pearl industry, both saltwater and freshwater.
Keshi Pearls are Pearls with no nucleus, forming in the Pearl sac where an implanted nucleus introduced by a Pearl farmer has spontaneously been rejected. Sometimes the Pearl sac has split, forming a secondary cavity where a secondary Pearl forms with no nucleus.
Having no nucleus, Keshi Pearls are all nacre
down to the middle like natural Pearls, so they are sturdier and less prone to wearing out. Yet they are not true natural Pearls, because they are from cultured or farmed mollusk
s. Having no armature around which to grow, these Pearls take on a free-form aspect and can have a number of shapes, including being cupped like cornflakes or forming pebble shaped baroques.
Keshi Pearls can grow anywhere that Pearls are cultured, and they can range in size from a small seed to a golf ball. Because they are all nacre, they have a high luster and a wide variety of colors, though many are gray with overtones. This, along with their free-form shapes, makes them invaluable to jewelers creating unique art pieces.
Although Keshi Pearls began as a plentiful offshoot of the cultured pearl industry, they are beginning to be more of a rarity, as the South Sea and Tahitian Pearl farmers, in particular, now use x-rays to determine whether nuclei have been rejected. If so, the oyster is reimplanted, giving keshi no opportunity to grow. Smaller keshi Pearls, less than two millimeters, from freshwater mussels and Akoya oysters remain plentiful, though they have less value.