Natural Pearls, rare beauties of the natural world, and how we identify them

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Natural pearl necklace: Lot 261 in Dupuis Spring 2014 Auction, sold for $60,000 http://bit.ly/DUPUIS-LOT-261

Natural pearls are a very rare thing. They have grown by accident, and are the product of incredible good fortune. Once upon a time people would dive, time after time, into the ocean, searching for the one elusive “oyster” that was bearing the extraordinary gift of a pearl. These natural pearls are very rare, and highly desired today.

The translucency of the pearl material called “nacre” gives natural pearls a radiance that is unlike anything else. This translucency allows light to penetrate the natural pearl and produces reflection of light and iridescence, often in a rainbow of colours, sometimes referred to as “orient” or “overtones”.

What gives value to a pearl is its size, the smoothness of its surface, the roundness of its shape, its body colour, the colours of the “overtones” seen in each, and the matching of the pearls if there are more than one.

One of the ways that we distinguish natural pearls from cultured pearls is that cultured pearls usually have a bead of mother of pearl inside, and a layer of the pearl material called nacre laid on by the mollusc, or “oyster” on the outside, and natural pearls are layers of nacre all the way to the centre, with no bead.

We can X-ray pearls to detect a bead, or sometimes we can look down the drill hole to detect a bead. In natural pearls we often see layer after layer all the way to the centre of the pearl. Following are some images of the layered structure seen in some of the natural pearls in the necklace shown above.

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Looking down the drill hole of a natural pearl

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The layered structure seen down the drill hole in a natural pearl

Duncan Parker

About Duncan Parker

Duncan Parker, FGA, FCGmA, CAP (CJA), Vice President. Duncan is a columnist and contributor for industry magazines and journals. He has been an instructor of the gemstone course at Ryerson University, the Gemmology courses of George Brown College and Canadian Gemmological Association as well as instructor Master Valuer Program with the Canadian Jewellers Association. A renowned expert, he speaks regularly at international gem and jewellery conferences and symposiums, as well as at less formal events. He has served as President of the Canadian Gemmological Association since 1995. Before joining Dupuis Auctioneers, Duncan was a director of research at Harold Weinstein Ltd., a leading and respected jewellery appraisal company.
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