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Sunday, December 31, 2006

The Beauty of Black Tahitian Pearls

The Pacific Ocean is home to the black-lipped oysters that produce large Tahitian pearls. The ocean waters are warm, and this allows the oysters to grow much larger than in other areas, thus producing larger pearls. Tahitian oysters are farmed in large sheltered lagoons that are kept free of pollution and overcrowding. Water temperatures and nutritional levels, as well as environmental and biological conditions are monitored carefully. These well cared for oysters are responsible for producing the beautiful Tahitian Pearls.

How a Tahitian pearl is formed

Aragonite, which is a form of calcium carbonate, is secreted by the pearl oyster. This substance coats the inside of the oyster shell and produces the “mother-of-pearl” lining. It also forms the layers of the pearl. The oyster can produce aragonite secretions up to four times a day with each secretion forming another layer. The layers are about one micron or 0.001mm thick. Tahitian oyster live for about two years which means they produce up to about two thousand layers; more than most other pearls. The light passes through these multiple microscopic layers and is reflected and refracted to produce a shimmering effect. This shimmering creates magnificent colors which seem to travel and move throughout the pearl. This is part of what makes the Tahitian pearl so unique.

Criteria

Pearls are graded based on certain criteria. These are:

• Size – the expensive pearls are the larger ones. The Robert Wan Pearl is the largest Tahitian Pearl and it measured over 20.92mm or 13/16 of an inch in diameter. Tahitian pearls usually measure between 9mm and 14mm and are considerably larger than Chinese or Japanese pearls.

• Pearl Thickness – layers surrounding the nucleus.

• Shape – round pearls are the most sought after and cannot vary more than 2% from being perfectly spherical. Tahitian pearls can also be semi-round and semi-baroque.

• Surface Purity – surface imperfections on the pearl.

• Quality – the luster and the imperfections of the pearl.

• Brilliance – the orient and the luster of the pearl. The orient, which is the shimmering quality of the pearl, is very noticeable in Tahitian pearls.

Colors

Although Tahitian pearls are naturally black, they are very unique in their coloration. The pearls highlights can be silver and even gold. The overtones on a Tahitian pearl can be blue, purple and even green. The variations in the colors of the pearls make very striking jewelry when combined with other gemstones and metals.