Nucleation
The operation that starts a cultured pearl: inserting a bead, a piece of mantle tissue, or both.
A technician opens the mollusc slightly and places the implant into the gonad or the mantle, along with a graft of donor tissue.
The donor animal is what determines colour, not the host, which is why farms select donors carefully.
It is delicate surgery with real mortality. A meaningful share of nucleated molluscs die or reject the implant before harvest.
When you are buying
Rejection is why keshi pearls exist and part of why pearls cost what they do. A large share of every crop never becomes a saleable pearl.
Pearl Sac
The pocket of tissue that forms around an implant inside a mollusc and secretes nacre onto it.
Bead Nucleated
Grown around a round shell bead, so the pearl is a nacre shell over a core. The saltwater method, and how roundness is achieved.
Tissue Nucleated
Grown around a scrap of mantle tissue instead of a bead, so the pearl is solid nacre throughout. The freshwater method.
Keshi Pearl
A pearl that forms by accident with no nucleus at all, so it is solid nacre. Irregular in shape and unusually bright.
Pearl Farming
Growing pearls deliberately: nucleating molluscs, tending them in water for months or years, then harvesting.