Part 4 - Quality criteria

a) Nacre thickness

This affects the durability and sometimes the beauty of a  Tahiti cultured pearl. 
During processing, handling and wearing, a pearl's relatively soft and delicate nacre inevitably suffers some abrasion. If a cultured pearl starts off with a thick coating of nacre (and gets reasonable care), the abrasion will not affect its beauty for many years. If, however, the pearl has a thin nacre coating (or is carelessly treated), its nacre will soon wear away, exposing the nucleus.

b) Luster

This is the quality of the light reflections from the pearl's surface. Pearls are said to have high, or very high, luster when the reflections are bright and sharp. When the light reflections are weak and fuzzy (or diffused), the pearls are described as dull.

The Tahiti cultured pearl rivals anything grown in Japan for the sharpness and intensity of reflected light from a pearl's surface. In fact, pearls from French Polynesia often possess such a mirror-like finish and radiant brilliance that their overall appearance is likened to that of very shiny metallic objects, such as ball bearings.

The only problem with such an analogy is that it suggests a cold, steely beauty. In reality, lustrous Tahiti pearls have a warmth to them -even when their surfaces gleam as brightly as a dress shoe.

No wonder, then, that luster is one of the most prized factors of Tahitian pearl beauty. And rightly so. Most jewellers probably don't know that the typically high-gloss finish of the Tahitian pearl is something unique to the cultured variety of this gem.

The result is that the degree of preferred luster varies from fine jeweller to fine jeweller. Some, recalling that natural black pearls generally had for more of a matte finish, prefer Tahitian cultured pearls with soft, satiny surfaces reminiscent of the natural variety. Others prefer the high-glow pearls at which Tahiti excels. If lustre is one of the features that sets apart the cultured from the natural black pearl, they'll tell you, this should be played up, not down.

Still other jewellers who sell a wide variety of Tahitian cultured pearls take a pragmatic, best-of-both worlds approach. Regardless, the luster of the Tahitian pearls is just like their color--all natural.

c) Surface

Pearl dealers talk about the degree to which a pearl's skin is free of blemish as "spotting", a very negative term for a very common pearl feature.

Pearl dealers prefer the neutral term "surface" as a way of discussing -or even rating- the presence or absence of imperfections in pearls. In this regard, it is the pearl world equivalent of "clarity".

Tahiti cultured pearl farmers generally use four ratings for surface quality A, B, C and D.

Quality A pearls are entirely smooth or are marred with just one or two tiny ripples or indentations (often hidden later by a drill hole) that are visible to the naked eye but are confined to less than 10% of the surface. They all have a very good luster. But a nearly negligible number of pearls merit this rating. Their extreme rarity also adds significantly to their cost. For the most part, jewellers will see pearls that deserve grades of B or lower.

Quality B pearls are those with some imperfections concentrated over less than a third of their surface and with a beautiful or average luster.

Quality C pearls are those with light concentrations of imperfections over less than two-thirds of their surface and an average luster. Given the girth of most Tahitian pearls, plus their dark tones and/or color play, gem stones used with C graded Tahitian pearls are still often quite attractive.

Quality D pearls are pearls with light imperfections over more than two-thirds of their surface and no deep imperfections; or quality D pearls are those with deep concentrations over less than half of their surface and with a soft luster. This is the lowest grade of all. There are many pearl dealers, jewellry designers and jewellers who believe such unsightly pearls should be labeled "rejection goods" and barred from commerce.

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