Origin of Name :-
The name refers to an exquisitely designed necklace
whose predominant component is black Tahitian keshi pearls, followed by
aquamarines and diamonds, that appeared at a Bonhams Natural History
Auctions, held on December 6, 2009, at Los Angeles, California. The
extraordinary beauty of this necklace is undoubtedly due its innovative
design using baroque-shaped, large, black Tahitian keshi pearls. No two pearls
in the necklace have identical shapes, but thanks to the ingenuity of
the designer, these unique individual pieces of irregular shaped
pearls has been put together, in such a way as to give a semblance of
symmetry. In other words the designer in creating this unique piece of
jewelry has attempted to create order from disorder, represented by
highly irregular pieces of black Tahitian keshi pearls, in which no two
pieces are identical. The necklace represents a synthesis of three main
categories of gemstones, organic stones (pearls), colored stones
(aquamarines) and diamonds, which is reflected in the name of the
necklace.
Black Tahitian Keshi Pearl, Aquamarine and Diamond
Necklace
Characteristics of
the necklace
The necklace which is 16 inches (40.6 cm) long, falls
within the category of a choker, whose length varies from 14-16 inches
in the Mikimoto classification of necklaces. A pendant made up of the
same gemstones as the necklace, hangs from the middle of the necklace,
forming its centerpiece. The entire necklace is made up of 33 cultured
black color Tahitian keshi pearls, varying in size between 10-15 mm.
There are five black keshi pearls in the pendant, all of which are
baroque in shape, and non-identical. However, three of these pearls, the
upper most and two pearls on the sides, arising from the middle pearl,
have a somewhat irregular drop shape. Pear-shaped aquamarines and small
rose-cut diamonds are interspersed between the pearls, and mounted on
white gold. There are seven aquamarines on the pendant, which is
suspended from the lower end of the necklace, at which point a pair of
baroque pearls are mounted.
There are five pairs of these baroque pearls on this
necklace, and the designer has tried as much as possible to pair
together pearls that have almost identical size, shape and color. The
pairs of pearls are placed symmetrically on the necklace. Two single
baroque pearls are placed in between the pairs of baroque pearls, making
a total of eight single pearls. Ten single baroque pearls are placed one
after another on the rear of the necklace, without any diamonds or
aquamarines in between them. Thus in the necklace there are 18 single
pearls and 5 pairs of pearls, making a total of 28 pearls, which
together with the 5 pearls on the pendant gives a final total of 33
baroque pearls.
The pear-shaped aquamarines in the necklace are
placed closer to the five pairs of baroque pearls, and on either side of
the pairs. There are three pear-shaped aquamarines on either side of
each pair of baroque pearls, making six aquamarines for each pair, and
30 aquamarines for the 5 pairs of baroque pearls. The 30 aquamarines on
the necklace together with the 7 aquamarines on the pendant, give a
total of 37 aquamarines, which has a total weight of 15.68 carats. Small
rose-cut diamond accents are placed only at one point on the pendant,
where it joins the necklace, and four symmetrical points on the lower
part of the necklace, between the single baroque pearls. The total weight of
the diamond accents is 0.62 carats.
The definition of
keshi pearls by the International Jewelry Confederation (CIBJO)
Early definition
included only non-nucleated pearls produced accidentally or
spontaneously in Akoya pearl oysters
The International Jewelry Confederation going by the
French acronym CIBJO has defined keshi pearls as non-beaded cultured
pearls, formed accidentally or intentionally by human intervention in
marine pearl oysters such as the Akoya oyster (Pinctada fucata),
Silver/Gold lipped oyster (Pinctada maxima) and Black lipped oyster (Pinctada
margaritifera), and is a by product of the culturing process. The
definition reflects the genesis of keshi pearls, which first came to
prominence as a by product of Akoya pearl cultivation in Japan. The
pearls were found to be non-nucleated and made of nacre only and formed
accidentally or spontaneously, as a result of the oyster rejecting the
implanted bead nucleus, but retaining the mantle tissue implant, which
formed a single pearl sac or several pearl sacs after fragmentation,
leading to the formation of one or more non-nucleated nacre-only pearls
inside the oyster, usually less than 2 mm in size, and hence known as
keshi (seed) pearls by the Japanese. The cause of the oyster rejecting the bead nucleus is
unknown. Due to the spontaneous provenance of these pearls, some
gemologists believe that keshi pearls should be classified as natural
pearls.
Another possible way of keshi pearls developing
accidentally, was for the bead nucleus to remain intact, but tiny
fragments of mantle tissue to separate and move away from the nucleus,
and form several pearl sacs. Thus a bead nucleated pearl and several
keshi pearls develop within the same oyster. However, the nucleated
pearl will be small, as part of the nacre is used for forming keshi
pearls. The two accidental methods given above can be attributed to the
behavior of the oyster, and the pearls formed may be considered as
natural.
However, there are also accidents caused by man, such
as accidental contamination of the pearl-forming tissues of the oyster,
during implantation, with fragments of mantle tissue, shell bead,
parasites and even sand particles, that causes irritation and the
formation of pearl sacs. Keshi pearls produced by accidental
contamination cannot be considered as natural pearls.
Later definition
expanded to include intentionally produced non-nucleated pearls too, not
only from Akoya oysters, but also from South Sea and Black Tahitian
pearl oysters.
Keshi pearls were produced intentionally by Akoya
pearl farmers in Japan by implanting only mantle tissue in saltwater
oysters, after there was an unexpected demand for these pearls from the
Middle Eastern Arab countries, where there was a great demand for
natural pearls, and the people were averse to wearing jewelry made of
cultured pearls, which oysters had been forced to grow. Thus the
definition of keshi pearls was expanded to include also intentionally
created keshi pearls from saltwater oysters. Later with the development
of the cultured pearl industry in Australia based on the Silver/Gold
lipped oyster (Pinctada maxima), and the South Pacific including the
Tahiti islands, based on Black lipped oyster (Pinctada margaritifera),
the formation of keshi pearls were also reported from these areas, as a
by product of their pearl industry. Accordingly, the definition also
included keshi pearls produced by these oyster species, even though the
pearls produced were much larger, reaching a size of 10-15 mm.
Two important
qualifications in the CIBJO definition
Two important qualifications in the CIBJO definition
of keshi pearls, are that they are "cultured" and produced by "marine
oysters only." The CIBJO does not recognize keshi as natural, even
though some of them are produced spontaneously like natural pearls, and
are composed of nacre only, imparting a luster and orient similar to
natural saltwater pearls. Perhaps, the reasons that prompted them not to
classify them as natural was that the pearls were still a by-product of
the culturing process and that there was no way of distinguishing a
spontaneously produced keshi pearl from an intentionally produced one.
The qualification "marine pearl oysters" came after representations made
by the gem and jewelry trade to restrict the term "keshi" only for
pearls produced by marine pearl oysters, after the Japanese introduced
the lesser quality freshwater keshi pearls to the markets, following the
development of the freshwater pearl culturing industry in the early
1960s.
Japanese and the
Chinese extended the term keshi to include pearls produced by freshwater
musssels
The Japanese used the term keshi for all freshwater
pearls produced by freshwater mussels, because technically speaking
these pearls are also non-nucleated and produced around mantle tissue
like keshi pearls. The Chinese also use the term keshi to refer to their
cultured freshwater pearls, but only for the second and third generation
pearls, which are thin and flat, and produced without any implantation.
The first generation pearls which are plump and full with desired shapes
are not referred to as keshi, by the Chinese. However, the term "keshi"
as used by the Japanese and Chinese pearl culturists, is not recognized
by the CIBJO.
Properties of black
Tahitian keshi pearls
Size of the black keshi
pearls
The size of black Tahitian cultured pearls vary from
about 8 mm to 20 mm, giving an average of 14 mm. The black Tahitian
keshi pearls which are smaller than their bead nucleated counterparts
have a lower range, varying from about 5 mm to 15 mm, giving an average
of about 10 mm.
Shape of the black keshi
pearls
Like all keshi pearls, black Tahitian keshi pearls
are also mainly irregular or baroque in shape, as they have no bead to
guide their growth. No two black keshi pearls can have identical sizes
and shapes, as seen clearly in the accompanying photograph of black
Tahitian keshi pearls. In fact the beauty and romance of these pearls
lie in their odd shapes, highly valued by jewelry designers because of
the immense opportunities presented for the creation of innovative
designs, like the pearl necklace which is the subject of this webpage.
Black Tahiti Keshi Pearls
Color of the black keshi
pearls
The black color of Tahitian pearls is caused by
melanin pigments, secreted by special glandular cells in the mantle, at
the time of nacre formation. Melanin combines with conchiolin the
protein component of nacre. Aragonite, the non-protein component of
nacre, composed of calcium carbonate, remains colorless and transparent,
through which the black color of melanin shows through. Black and gray
are the main body colors of black Tahitian pearls, as well as black
Tahitian keshi pearls.
Overtones of the
black keshi pearls
Apart from the black body color, black Tahitian keshi
pearls also show a variety of overtone colors, which are translucent
colors, appearing on top of the pearl's main body color, that tend to
modify the body color and add depth and glow to a pearl. Overtone colors
are not caused by pigments, but are optical effects like iridescence,
caused by the interference of light as it passes through alternative
layers aragonite and conchiolin, and is dependent on the thickness of
the nacre. Keshi pearls being made of nacre only, have a very high
luster, orient and overtones, properties that are dependent on the
thickness of nacre.
The basic body color of black keshi pearls, the
possible overtone colors and the modified color of the pearls are given
in the following tablle :-
Combination of body
color and overtones in black Tahitian pearls
|
S/N |
Basic body color |
Overtone |
Combination |
Special name |
|
1 |
gray |
yellow |
yellowish-gray |
Champagne |
|
2 |
black |
purple |
purplish-black |
Cherry |
|
3 |
black |
blue |
bluish-black |
Lavender |
|
4 |
pale gray |
- |
pale gray |
Moon Gray |
|
5 |
black |
green |
greenish-black |
Peacock-green or black-green |
|
6 |
black |
rainbow of colors |
- |
Peacock or Rainbow |
|
7 |
black |
reddish-purple |
- |
Aubergine or Egg plant |
|
8 |
gray |
purple |
purple-gray |
Pigeon Gray |
|
9 |
gray |
green |
greenish-gray |
Pistachio |
|
10 |
gray |
- |
gray |
Silver |
|
11 |
black |
gold |
golden-black |
Tahitian Gold |
The presence of overtones enhances the value of black
Tahitian pearls and their keshis. The most sought after combination of
colors in black Tahitian pearls, are Peacock, the combination of black
and rainbow; Peacock-green, the combination of black and green; and
pistachio, the combination of gray and green.
The source of black
Tahitian pearls
The geographic range
of Pinctada margaritifera the oyster species that produces black
Tahitian pearls
The oyster species that produces black Tahitian
pearls is Pinctada margaritifera, whose natural habitat is the
Indo-Pacific waters, extending from the Persian Gulf in the Indian
Ocean, through the South China Sea and the Pacific Ocean to the Gulf of
California in North America. In the Pacific Ocean, the range of Pinctada
margaritifera extends from Japan to the Southern Pacific Islands of
French Polynesia, reaching its greatest abundance in the atoll lagoons
of Eastern Polynesia. The origin of the black Tahitian pearls in the
atoll lagoons of Eastern Polynesia, is the oyster species known as
Pinctada margaritifera cumingi, which has a life span of about 30 years,
growing to a maximum size of about 30 cm, weighing up to 5kg. The
oysters maximum pearl productive period is when it is 3-7 years old,
having a diameter of 15 to 20 cm.
Tuamotu Archipelago
was the main source of natural black Tahitian pearls in ancient times
The main source of natural black Tahitian pearls
since ancient times had been the Tuamotu Archipelago, situated about 300
km northeast of Tahiti. The islanders of Tuamotu, used natural black
Tahitian pearls as a currency to purchase goods brought from Tahiti. The
European and American explorers exploited the black-lipped pearl oyster,
mainly as a source of mother-of-pearl for the shell button industry. The
continuous exploitation of the oyster for over 70 years from 1802 to
1880, led to serious depletion of oyster populations, and the foreigners
abandoned the atolls in 1880. Any black pearls recovered as a by product
of the industry, was sold in the pearl markets of the world.
History of the black
cultured pearl industry in the French Polynesia
Kokichi Mikimoto was
first person to culture black pearls using Pinctada margaritifera in
1931
After Mikimoto successfully cultured Akoya pearls in
1916, leading to the establishment of hundreds of pearl farms producing
millions of cultured Akoya pearls annually, he diverted his attention
towards the culturing of black pearls using the oyster species Pinctada
margaritifera. At first he set up a farm on the Ishigaki Island in
Okinawa to culture the black-lipped oysters, but it was not until 1931
that he was first able to culture black pearls, which eventually entered
the pearl markets in the late 1930s.
The contributions of
Jean-Marie Dornard, Jean-Claude Brouillet and Robert Wan in the
development of the cultured pearl industry in French Polynesia
The first successful culturing of black Tahitian
pearls was achieved in 1962 by the French Scientist Jean-Marie Dornard
who nucleated about 5,000 oysters in two experimental farms in Hikueru
in the Tuamotu Archipelago and Bora Bora in the Society Archipelago,
applying Mikimoto's technique, and harvesting around 1,000 high-quality
Tahitian black cultured pearls. Following this success more pearl farms
were opened in both archipelagos and French Polynesia attained
international recognition as a source of black Tahiti pearls. But, the
actual international popularity of black Tahitian pearls came after
1975, when production from a pearl farm owned by the French businessman
Jean-Claude Brouillet in South Marutea that employed the services of
skilled Japanese pearl culturists and technicians, hit the international
pearl markets. In 1984, the ownership of Brouillet pearl farms were
acquired by another renowned pearl culturist Robert Wan, who worked in
close collaboration with the Tahitian Government, with the twin
objectives of popularizing the high-quality black Tahitian cultured
pearls in the international pearl markets, and making cultured pearls
the country's main export commodity. Robert Wan expanded production by
opening new pearl farms, and introduced quality control measures that
enhanced the worldwide reputation of black Tahitian cultured pearls. In
recognition of his contribution to the Tahitian pearl industry, he is
popularly referred to as the "father of the Tahitian pearl."
The culturing process
of black Tahitian pearls
The first step in pearl cultivation is the collection
of spats (d-shaped larvae more than 24 days old) that are about to
attach to a surface such as a coral reef and begin growth, by laying out
spat collectors at the bottom at the bottom of the lagoon, during the
reproductive period, from October to February. When the spats have grown
to young oysters of a certain size, they are transferred to protective
baskets which are placed in deep water areas of the lagoon for 2-3 years
until they become pearl productive (2.5 to 7.0 years). The protective
nets are then transferred from deep waters to holding platforms near
seeding laboratories, until the oysters are seeded. Seeding is done in
surgically clean laboratories using sterilized equipment to reduce the
chances of infection, and keshi pearl formation. Cutting instruments
used are razor sharp to reduce the trauma on the oysters, and
antibiotics are used to prevent infection. Oysters removed from the
protective baskets are scraped and cleaned before opening. The valves of
the oyster are opened carefully by the pearl technician, who then makes
a small incision on the gonad with his razor sharp scalpel. A sterilized
mother-of-pearl nucleus (from a Mississippi freshwater mussel) is
inserted into the incision, followed by a small piece of mantle tissue
from a sacrificial oyster, such that the mantle tissue lies between the
bead and the gonad, with the side containing epithelial cells facing the
nucleus. The valves are then closed and the grafted oysters transferred
back to the protective baskets, which are then transferred back to the
deep waters of the lagoon, for the husbandry or growing out period,
which generally lasts for about two years. However, from time to time
the baskets are hauled up and the external surfaces of the oysters
cleaned to remove marine growths that can harbor parasites and diseases.
Harvesting of
cultured black Tahitian pearls and keshis formed in oysters that have
rejected the graft
After two years the seeded oysters are brought back
to the holding platform near the laboratories for harvesting. The
oysters are removed from the baskets, cleaned and opened gently, and the
cultured pearl extracted from the gonad. If the pearl is of good
quality, the oyster is selected for a second grafting, and a second
nucleus is quickly inserted followed by a small piece of mantle tissue,
and the valves are closed again, and transferred to the protective
baskets, for the second grow out period. During harvesting oysters are
often discovered that have rejected the first graft and formed "keshis."
Such oysters are not chosen for a second graft, so also are oysters that
have a sickly appearance. Robust and healthy oysters are sometimes used
even for a third graft, but generally the quality of the pearl decreases
as the number of grafts increase, due to the increase in age of the
oyster. Even though several graftings are possible in the black-lipped
oyster, it is important to note that unlike freshwater mussels, these
oysters can only take one graft at a time. Thus cultured black Tahitian
pearls as well as cultured black Tahitian "keshis" are much scarcer than
freshwater cultured pearls or their "keshis."
Tahiti pearls are not
actually produced in island of Tahiti, but in other islands in the five
island groups of French Polynesia
Tahiti is the largest and most densely populated
island in the French Polynesia, which is part of the Society Islands
group, and the capital city Papeete is also situated in this island. Even though the black cultured pearls produced in French
Polynesia are known as Black Tahitian pearls, most of these pearls are
not produced in Tahiti, but in various other islands, in the five island
groups of the French Polynesia, chief among which are the islands of the Tuamotu archipelago such as Hikueru, Fakarava, Rangiroa, Manihi and
Tikehau situated about 300 km northeast of Tahiti and the Society
Islands Group, such as Bora Bora, Tahaa, Huahine, and Raiatea, situated
about 200 km northwest of Tahiti.
Map of the French Polynesia in the South Pacific Ocean
The Black Tahitian
Keshi Pearls, Aquamarine and Diamond Necklace appears at the Bonhams
Natural History Sale on Dec 6, 2009
The Black Tahitian Keshi Pearls, Aquamarine and
Diamond Necklace came up for auctions at the Bonhams Natural History
Sale No, 17535, held on December 6, 2009, in Los Angeles, California.
The necklace was assigned Lot No. 2358 and a pre-sale estimate of USD
6,000 to 8,000 was placed on the necklace. However, the necklace
remained unsold at the auction.
You are welcome to discuss this
post/related topics with Dr Shihaan and other experts from around the
world in our
FORUMS (forums.internetstones.com)
Related :-
1)
Birk's Black Tahitian Double Row Pearl Necklace
2) Nina Dyer Pearl Necklace
3) Drexel Pearl
4)
Keshi pearls - Non-nucleated Cultured Pearls
Formed Accidentally or Intentionally in Marine Oysters.
References :-
1) Black Color Keshi Pearl, Aquamarine and Diamond
Necklace - Lot No. 2358. Bonhams Natural History Sale 17535, 6 Dec 2009
2) Keshi pearls - Non-nucleated Cultured Pearls
Formed Accidentally or Intentionally in Marine Oysters.
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