How pearl oysters are farmed for pearls
A cultured pearl begins as a surgical graft, a shell bead and a scrap of tissue from a donor oyster.
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The short version
Pearl oysters are saltwater bivalves with a thick lining of nacre, and farmers run them as living pearl makers. A technician implants a polished shell bead and a scrap of mantle tissue from a donor oyster. The tissue forms a sac that coats the bead in nacre, and some oysters survive to take a larger bead.
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Raise the young shellfish
These oysters belong to the genus Pinctada and are not closely related to the edible kind. The big South Sea species is raised until it is about 2 years old before its first seeding.
about 2 years old at first seeding
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Graft bead and tissue
A technician places a polished bead, cut from freshwater mussel shell, inside the host along with a small piece of mantle tissue from a donor. The tissue makes a pearl sac around the bead.
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Let the nacre build
The sac secretes layer after layer of nacre, made of calcium carbonate and a fibrous protein. Oysters hang in the sea, and each layer thickens the pearl.
twelve to eighteen months for a beaded pearl
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Open the shells and sort
Pearls are taken out and graded. Sea oysters usually carry one bead at a time, so volume stays low, while freshwater mussels take many grafts.
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Reseed the survivors
South Sea and Tahitian oysters that survive the harvest are often given a new, larger bead in the same operation. They can be reseeded up to 3 or 4 times.
Worth repeating
- Before pearl farming, divers might find only three or four perfect pearls in a haul of three tons of oysters.
- X-rays tell cultured from natural pearls, because a bead shows a solid center without growth rings.
- A keshi pearl is made entirely of nacre when the tissue slips off the bead.
Where it goes next
Pearl oysters feeds 1 line directly.
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Sources
Cite this page: "How pearl oysters are farmed for pearls." Assembly Line, 2026-11-03. https://assemblyline.org/make/pearl-oyster