COLOR IN CULTURED PEARL HAS MANY CAUSES

By Francisco Javier Fernandez Sanchez

Quick answer: A cultured pearl’s color comes from several natural causes: the species of oyster, the color of its shell’s inner nacre, trace elements in the water, and how light interferes across nacre layers to create overtones. In Tahitian pearls (Pinctada margaritifera) the dark body color is natural, set by the black-lipped oyster.

The color of a cultured pearl is set by several natural factors at once. Organic pigments in the nacre play a part, and so does the water the oyster grows in — sea water and freshwater carry different concentrations of trace elements such as manganese, and that chemistry leaves its mark on the nacre. But the single biggest factor is the mollusk itself, and specifically the donor animal. In pearl farming a small piece of mantle tissue, called the saibo, is grafted into a host oyster to start the pearl sac, and that graft is what tells the new nacre what color to be. Xenotransplantation experiments — grafting tissue from one species into a host of another — have shown that color is driven mainly by the genetics of the graft, not the host.
That is also why color matters so much in the lab. Reading the way color sits in the nacre is how a gemologist tells a natural color from a treated one — dyeing, heat or bleaching. The black-lipped oyster Pinctada margaritifera carries mantle cells that lay down dark, earthy-toned nacre, the same color you see lining its mother-of-pearl shell. So its cultured pearls come out naturally dark — grey, charcoal and aubergine with peacock overtones — exactly as the oyster intends, and never by dye.
#southseapearls #tahiti #indonesia #myanmar #pearls #culturedpearls #australia

COLOR IN CULTURED PEARL HAS MANY CAUSES

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