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Birth of a Pearl
 A cultured
pearl is a true jewel of the sea. It owes its beauty to the creative
forces of nature. While precious stones must be polished before they
sparkle, pearls already have a warm natural glow.
The birth of a pearl begins when a foreign substance, such as a grain
of sand, finds its way into the oyster's body and causes an
irritation. The oyster then takes a defensive action by secreting a
substance called nacre which builds up around the irritant. The layers
of nacre secreted onto the irritant develop into a smooth, hard
substance. After many years of this process, a pearl is formed.
 Cultured pearls
are made in much the same way as natural pearls by utilizing a
technique known as grafting.
The grafting technique consists of introducing a perfectly round
nucleus, fashioned from the shell of a mussel cultivated in the
Mississippi, into the gonad of an oyster.
A small piece of mantle from another oyster is inserted along with the
graft. The cells from the sacrificed oyster develop around the
implanted nucleus thus forming a pearl sack which, once closed, will
secrete pearl material.
Before undergoing this grafting process, the oyster submits to a fast
for several days in order to slow down its metabolism which decreases
the risk of rejection.
Many people still make the mistake of believing that cultured pearls
are imitations or fake ones. In fact, cultured pearls result from the
same natural phenomenon as natural pearls -- it is just that this
phenomenon is induced by the grafter. In other words, man plays the
part of nature by introducing the irritant or nucleus into the oyster
and then steps aside to allow nature to create its miracle.
The
Beginning Of Pearl Culturing In Polynesia
Robert
Hervé was the first to experiment with pearl culturing in Polynesia.
He settled in the Tuamotus and built a fare or bungalow on piles over
the lagoon of Apataki where he carried out his studies. After failing
to produce large numbers of the pearls in the 1930s, he brought in
Japanese grafting specialists to help perfect the art of culturing
pearls in Polynesia. Today, the Tahitian black pearl is the number one
export item in French Polynesia.
The Giant South Sea oysters that are found in the warms waters of the
inter-tropical zone belong to the Pinctada family. These are highly
sought after and t hey produce pearls of an exceptional size in an
infinite range of colors. The shell of the Pinctada maxima with white,
silver or golden colored lips and that of the Pinctada margaritifera
with green or black lips, have always been prized for their
specificity's: thickness and quality of the nacre, depth and
brilliance of color.
 The Pinctada
margaritifera , variety Cumingi , named for the scientist who first
described them in 1820, exclusively populate the coral reefs of
Polynesian lagoons. Their giant shells are streaked with black lines
on a gray background and the lips are black. The inside edge of the
shell is splashed with iridescent glints of greens and blacks that are
absolutely unique and from which they take their Tahitian name of Poe
Rave or green black. In fact, they offer a fascinating diversity of
shades.
This aristocrat of turquoise-blue lagoons loves waters of between 24
and 29 C degrees. At 18 degrees C its growth stops and at 11 degrees
it dies. Such low temperatures are nonexistent around Tahiti and its
archipelagos.
Water density, the nature of the sea bottom and currents exert a
notable influence on its
growth. A strong Polynesian oyster will live to 30 years old, attain
the size of 30cm and can weigh 5kgs.
The average life span of the species is estimated to be between 10 and
15 years with a normal size of 15cm.
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When selecting a pearl, the following 5
criteria's should be considered: |
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1 - Shape / 2 - Size / 3 - Color / 4 - Luster / 5 -
Surface
SHAPE:
Round pearls are perfectly spherical and are the most
valuable of shapes. They are quite rare and are more expensive.
The pear shaped pearls are round pearls extended by a "Queue" at
one end.
Button-shaped pearls are half-spherical pearls with a flat shape.
Baroque-shaped pearls have an irregular shape and are often the
source of inspiration for unusual-shaped jewels and accessories.
Circled pearls have one or several furrows which encircle the
entire pearl.
SIZE: The average size of a Tahiti Black Pearl is 8mm to 11
mm in diameter. The larger ones are 12 mm to 14 mm, and it is rare
to find pearls that are as large as 15 to 18mm. In assessing the
value of a pearl, one takes into consideration the size of the
pearl itself, the size of the nucleus -- which is between 6mm and
9mm -- and most importantly, the thickness of the pearl layer.
While size is not actually a quality factor, it does have a
significant impact on price.
COLOR: Tahiti black pearls have a wide range of colors and
shades ranging from pearly white to deep black. Other color shades
are blue, green, aubergine, silver, copper or gold and amazingly,
some pure white or pink-champagne pearls can sometimes be
harvested. In selecting a color, the most flattering pearl for any
woman is one that compliments her complexion.
LUSTER: The formation of a pearl from a tiny bit of sand in
an oyster is a fascinating natural phenomena. The natural layering
process is not just a defense against an irritant caught in the
oyster, but it is also how a pearl gets its luster. The thickness
of the layers results from the oyster depositing about 1,000
layers of nacre which is secreted by the oyster. Each layer
measures a few microns and the thickness of each layer varies with
water temperature.
To truly admire the luster of a pearl, one should look at it under
sunlight.
SURFACE: The surface of a pearl should be free of
disfiguration or major blemishes. Slight blemishes or flaws on a
pearl are natural and might include small marks or scratches on
the surface or perhaps slight bumps or craters. It is often said
that "luster is what you see from across the room, not blemishes".
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Jewelers and Black Pearls
No matter what the shape, size, color or imperfections of black
pearls, jewelers are always able to "show off" the pearl by using
clever, yet elegant designs to enhance the good and hide the
imperfections. This is why, any black pearl is always valuable.
The
cost and purchase of Black Pearls
Obviously there is a very wide range of prices according to the
above criteria's of quality. But as an indication, from fair to good,
9 to 12 mm in size, the price can start at $200 to $2500. Larger size
and better grades will go to 3, 4000 Dollars and above.
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In Moorea, for beautiful pearls at a very good value we recommend Ron
hall's ISLAND
FASHION, near Cook's Bay.
He has a good selection of lose pearls as well as pearl jewelry |
Reading
If you are interested in reading more about the black pearls of Tahiti
we recommend the excellent booklet "Pearls of Tahiti" which is very
informative and well illustrated. It can be found in Tahiti at the
airport and some hotel bookstores, as well as at the Librairie Vaima,
2cd floor of the Vaima Shopping Center in Papeete. |
