Delicious Chocolate Pearls - 8mm to 9mmPrice is per 15. 5 inch string of these beautiful pearls. Maximum size in the string is 8mm to 9mm. Cultured pearls Most pearls these days are cultured. These natural freshwater pearls occur in mussels for the same reason saltwater pearls occur in oysters. Foreign material inside a mussel can't be expelled. To reduce irritation, the mollusk coats the intruder with the same secretion it uses for shell building, nacre. To cultivate a pearl, farmers slit