Tahitian Pearls: Origin, Colors, Sizes and Value

Tahitian cultured pearls are the dark saltwater pearls of French Polynesia, sometimes called black pearls.³ Like other cultured pearls, each one starts when a person implants a bead in a living oyster.

Where Tahitian pearls come from#

Tahitian pearls come from the black-lipped pearl oyster, Pinctada margaritifera, in the variety that French Polynesia’s pearl law names cumingii.^{2 3} It is the second largest of the pearl oysters, found across the Indo-Pacific and especially abundant in the atolls of Polynesia.⁹

The name is protected. CIBJO allows a place name only for pearls grown in that place, and defines a Tahitian cultured pearl as a naturally colored cultured pearl grown in French Polynesia in this oyster, around a bead inserted in its gonad.¹ The same oyster is farmed in the Cook Islands, Okinawa and other Pacific islands,⁶ but under those rules their pearls are not Tahitian.¹

In the trade, these pearls are also marketed as “black” South Sea or simply “black” cultured pearls.¹¹

Where Tahitian pearls are farmed#

French Polynesia’s pearl farms are in the Society, Gambier and Tuamotu archipelagos.⁷ The oysters are grown from spat, young oysters caught on collectors in the lagoons.⁶

French Polynesia has produced black pearls since the mid-1970s.⁹ A first government trial on Bora Bora in 1961 produced good black pearls but had no commercial follow-up.¹²

From 2005 to 2014, French Polynesia grew an average of 12.9 tonnes of pearls a year, worth an average of US$104 million a year, and its output rose from 9 to 15 tonnes a year between 2006 and 2014.⁹ Pearl culture there is second in value only to tourism.⁹ CIBJO estimates production at about 8 million pearls a year, with a retail value of about US$230 million.⁶

How Tahitian pearls are grown#

A technician places a shell bead and a graft of mantle tissue in the oyster’s gonad.¹ Within 14 days, the graft grows into a pearl sac that covers the bead, and the first nacre appears about 32 days after grafting.⁹

Tahitian cultured pearls are harvested after about 18 to 24 months,⁷ and CIBJO counts one bead-cultured pearl per oyster every two years.⁶ An oyster can be grafted again after a harvest, and one study found that these second-graft pearls improved in both size and shape.⁹

Tahitian sizes, shapes and colors#

Tahitian cultured pearls are typically 8–14 mm, within a range of 8–20 mm⁴, and pearls over 20 mm are rare. CIBJO says this oyster produces the largest of all black cultured pearls.⁶

CIBJO lists their shapes as round, oval, button, drop, circled and baroque⁶, and GIA says they are most often round, though any shape occurs.⁴

Their bodycolors are gray, greenish gray, black and brown³, and GIA names greenish gray as the most common.⁴ Most are shades of gray, and some are copper-colored, pistachio green or taupe. GIA says their iridescent purple, green, turquoise or pink orient is what makes them exceptional.¹³ CIBJO lists overtones that the trade calls peacock, green, cherry, aubergine, blue, pistachio, gold, silver and red.⁶

Quality factors and grading for Tahitian pearls#

Tahitian cultured pearls are judged on GIA’s seven value factors.¹⁴ A 2018 study of these pearls lists the criteria used to evaluate them as size, surface quality, luster, shape, color and darkness.⁷

French Polynesia’s pearl law classifies every Tahitian cultured pearl by general criteria, its size, weight, shape and surface quality, and by additional criteria such as color, assortment, pairing and nacre thickness.² The letter grades used in the trade are a separate matter; the page AAA pearl grades explains them.

The territory required at least 0.8 mm of nacre from 2005.⁸ Its 2017 pearl law ended that mandatory check, and the pearl service now measures nacre thickness only on request, as a paid service.^{2 8}

What affects the price of Tahitian pearls#

GIA’s journal notes that the most costly Tahitian pearls look black with high iridescence, but that the pearls vary greatly in color, shape and size, and so have a wide price range.¹² When other factors are equal, larger pearls are rarer and more valuable.¹⁵

Identification, treatments and imitations#

Pearls from the black-lipped oyster have a reflectance feature at 700 nm that is a key identifying sign, and pearls from the related Pinctada mazatlanica share similar spectral features.¹⁰

Under French Polynesian law, a Tahitian cultured pearl must be naturally colored and untreated, and treated pearls must be labeled with the word “traitées” (treated) or the name of the treatment.²

Treated pearls from this oyster have reached the market. “Chocolate” pearls were most likely made by bleaching black cultured pearls,¹⁶ and intense “pistachio” colors have been produced by treatment, although natural pistachio-like colors also occur.¹⁷ Other dark pearls can owe their color to treatment too: some gray or blue Akoya, for example, are irradiated to darken the shell bead inside.¹⁸

Caring for Tahitian pearls#

Tahitian cultured pearls need the same care as other pearls. Put them on after perfume and cosmetics,¹³ wipe them with a soft cloth dampened in clean water after wearing, and keep them away from acids, solvents, heat and ultrasonic cleaners.¹ The care section has the full routine.