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Demystifying The Mysterious Tahitian Black Pearl

Researched and presented by Tom Taffel, member SFGMS


Tom Taffel, member since 1975.


There are six criteria for evaluating black Tahiti cultured pearls:

These standards are as rigorous and precise as those determining the quality of a beautiful diamond.

Size

One of the most unique aspects of Tahitian pearls is their large Size. Pearls are measured by their diameter in increments of 0.5mm. Throughout history most pearls have been rather small, ranging from 4 to 7mm in diameter. By contrast, the smallest pearls from the black-lipped oyster (Pinctada margaritifera) range from 8mm to 12mm. Pearls over 16.5mm are very rare, and therefore more valuable. Exceptional specimens include the baroque pearl of 26.95mm in diameter, which can be seen in the Musee de la Perl located at Centre Vaima, Rue Jeanne D'Arc 98713, Papeete, Tahiti (Polynesie Francaise). The Museum is open daily from 8:00AM to 7:00PM. Tel. (689) 45 21 22.

Shape

The Shape of a pearl depends on many factors, including the biological forces on the environment, which can affect the secretion of the pearl sac, and the nature of mother-of-pearl itself. One can find pearls in round, perfect sphere, semi-round, slightly imperfect sphere, semi-baroque pear, tear drop oval or button shape. Baroques are irregular forms that don't fit into the above categories. "Ringed" is a subcategory characterized by multiple circles on or near the surface.

Perfectly round and symmetrical pearls are the rarest and most exceptional. They represent at maximum 5% of the harvest. This rarity makes them the most valuable. While round pearls are the most highly sought after for rings and necklaces, the other shapes often inspire designers to create unique jewelry.

Color

A pearl gets its Color from the mantle tissue of its parent. "Black" pearls come from the black-lipped oyster, Pinctada margaritifera. Despite their name, these pearls, which are called Poe Rava in Tahitian, are not necessarily black. The basic black or gray of the Tahitian pearl gives rise to a multitude of tones from white to lunar gray/lunar blue, in an amazing palette of tints of the most astonishing hues: creamy, peacock, green, eggplant, blue, pink and golden.

Even if peacock, green and eggplant are the most sought after for their rarity, all the colors produced by the Pinctada margaritifera have their own originality and richness.

Luster

Reflection: light bouncing off the surface of the pearl. The surface of the pearl acts like a mirror. The smoother the surface, the brighter the pearl will appear. This smoothness is part of what gives Tahitian pearls their superior reflective quality known as luster. Cultured Tahitian pearls tend to have a very high luster. Some are so lustrous that they have an almost mirror-like quality. Interestingly, the luster of cultured Tahitian pearls is significantly greater than their natural counterparts.

Orientation

Refraction: light passing through the pearl. The transparent aragonite that makes up the layers of the pearl, acts like a prism, bending the light as it passes through the pearl. Some of the light bounces off the layers. The more transparent these layers, the easier it is for the light to pass through and reach deeper into the pearl. Orient is the iridescence from the light reflected from the inside of the pearl. If the layers of translucent aragonite are perfectly aligned, they act as a lens, bending the light. This light returns to the surface as the shimmering rainbow aura which is the hallmark of a quality pearl.

Reflection and Refraction combined produces "interference" causing the pearl to radiate iridescent light. The layers of aragonite work as a "diffraction grating" breaking the light into a shimmering spectrum. This is the effect known as "Orient" the moving rainbow of colors so remarkable in Tahitian pearls. Interference increases surface brightness, Luster, inner luminosity and orient, giving the impression of a glowing, translucent sphere. The larger the pearl, the more these light phenomena are pronounced. If the layer is too thin, the light tends to be diffused rather than reflected resulting in poorer luster and orient. On the other hand, the more layers of aragonite film there are, the larger the pearl and the more exquisite its luminous qualities to behold.

Surface Purity and Quality

Quality is determined by exterior imperfections and by the brilliance, (shine, sparkle or ability to reflect light). The best pearls are nearly featureless, with a high degree of translucency. The cultured pearls of Tahiti are precious jewels of high purity and rare quality which are grown under strict regulation by licensed producers.

The temperature of the water dictates both the thickness and the brilliance of the pearl. Warm waters promote the production of layers of pearl, whereas cooler water makes for finer and thus more transparent layers. The Pinctada margaritifera prefers the warm waters of the Pacific. Around the Gambier Islands, the Pinctada produces ultra-fine layers of aragonite; the substance that makes up the inner lining of the shell or the "mother-of-pearl" as well as the pearl itself. A Tahitian pearl has many thousands of layers of aragonite, depending on the length of time the pearl spends in the oyster. Each one is extremely thin and has the appearance of a transparent film. The archipelago is situated to the south of Tahiti where the water is cooler, so that the pearls acquire a particularly fine luster and orient.

Care and Feeding

Long Term Care of your beautiful black Tahitian pearls...Back pearls have a much thinner surface than white pearls and are (more) prone to cracking from dehydration. Your pearls should be hydrated one day per year in 10% salt water or ocean water. Mineral water or spring water can be used but not tap water. After a good 24-hour soaking, rinse well to remove salt from the string. Be sure to store your pearls away from other (harder) jewelry, which will scratch them.


Bora Bora Sunrise
Photo by Tom Taffel, July 25, 2006

If you're traveling to French Polynesia, and "the coral atolls that make Tahiti (Bora Bora in particular) the most beautiful island(s) in the world" (James Michener), you should take advantage of the opportunity to get some of these unique, rare and beutiful gems. In The United States, set pearls appraise at about four times their cost. Tahitian unmounted cultured pearls are exempt from all customs duties and entry taxes in the United States of America (duty free).

The duty free status for Tahitian black pearls was restored under the General System of Preference as goods considered as having come from an underdeveloped country. According to The BPGC, the only time duty does not apply is when the pearls are loose. As soon they have a clasp or are strung together there is a 16% local tax applied that you can reclaim before leaving Tahiti. Upon arrival in the U.S. you are allowed $800.00 per person on duty free items (set black pearls, perfumes, etc.) or $1,600.00 per couple. Above this amount, there's a 3% tax per thousand.

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