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French Polynesia Official Classification
Tahiti Cultured Pearls are pearl concretions that are secreted inside the
black-lipped Pinctada Margaritifera species of pearl oysters cultivated
mainly in the lagoons of French Polynesia. They consist of thick pearly
layers containing organic substances and calcium carbonate in the form of
aragonite.
In French Polynesia, the trade designation "Tahiti Cultured Pearl" is
reserved exclusively for cultured pearls obtained from a grafting of the
locally cultivated Pinctada Margaritifera, variety cumingi pearl oyster.
Such pearls have a continuous pearly layer over at least 80% of their
surface and do not reveal either the underlying nucleus.
Tahiti Cultured Pearls are classified according to their diameter, luster,
shape, surface purity and color.
Diameter
 
Pearls are classified from millimeter to millimeter and measured by the
shortest diameter, which generally ranges between 8 and 14mm. This is done
by sorting them through sieves. Some pearls reach 16mm and very
exceptionally 18mm. To date, the record diameter for a round pearl is 21mm,
24,6mm for a semi-round, 26,95mm for a baroque pearl (Exhibited in The
Robert Wan Museum of The Pearl)
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 Cultured Pearls have warmth to
them--even when their surfaces gleam as brightly as a dress shoe.
Regardless, the lustre of the Tahiti Cultured Pearls is just like their
colour--all natural. Shape
   
Four basic shapes are defined at the production stage:
# round and semi-round,(see photo 1)
# semi-baroque,(see photo 2)
# baroque(see photo 3)
# and ringed or circled.(see photo 4)
For some jewellery makers, shape is purely a design element, be it the
sensuous curves of the drop or the flowing free-form lines of many baroque
shapes. For such artists, all shapes that inspire them share aesthetic
equality.
Most designers agree it is difficult to favor one kind of shape over
another.
A New York designer once said: "A pearl that looks homely seen loose will be
transformed into a thing of beauty if placed in the right setting."
Quality
This is determined by observing the special features of the pearl's surface
and luster. But nacre thickness, color, shape and size also judge quality.
Nacre Thickness
This affects the durability and sometimes the beauty of a Tahiti cultured
pearl.If a cultured pearl starts off with a thick coating of nacre (and gets
reasonable care), its beauty will last a life time.
If, however, the pearl has a thin nacre coating (or is carelessly treated),
its nacre will soon wear away, exposing the nucleus.
The French Polynesian Government has set up a minimum nacre thickness of
0,8mm to the Tahiti Cultured Pearl. All pearls showing less than 0,8mm
thickness are banned for marketing and destroyed.
Surface
For reasons best understood by psychologists, 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.
Tahiti cultured pearl farmers generally use four ratings for surface
quality: A, B, C and D. 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 word equivalent of "clarity".
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