The great majority of Chinese freshwater cultured pearls are produced by implanting tissue pieces in the mantle of Hyriopsis cumingii mussels. Farmers have experimented with bead nucleation, but until recently the methods tried did not produce the quantity or quality necessary for economic success. In the late 1990s, Chinese researchers imported H. schlegelii mussels from Japan, began propagating them in hatcheries, and started cross-breeding them with native H. cumingii mussels. Using the two pure species and the hybrid, Chinese farmers produce tissue implantation-only cultured pearls and have developed a method called coin-bead/spherical-bead nucleation. This method has yielded significant quantities of jewelry-quality baroque shapes and lesser quantities of jewelry-quality rounds and near-rounds. Continued experimentation is expected to increase the percentage of rounds and near-rounds.