Origin of Name :-
The original
definition of "keshi" pearl
The word "keshi" in Japanese means "poppy" or "poppy
seed" and was first used by Japanese natural pearl harvesters to
describe tiny seed pearls sometimes found inside wild Akoya oysters (Pinctada
fucata), before Japan began the cultured pearl production. Such pearls
were too small to be drilled, and consequently had no apparent use in
the trade. Thus, what the Japanese originally referred to as "keshi"
pearls were tiny natural pearls harvested from some wild Akoya pearl
oysters, which were too small to be drilled.
Kokichi Mikimoto
develops a commercially viable method to culture spherical Akoya pearls
in 1916
Kokichi Mikimoto successfully developed a
commercially viable method to culture spherical Akoya pearls inside the
saltwater oyster species Pinctada fucata martensii, in 1916, adopting
the Mise-Nishikawa technique, in which a shell nucleus together with a
piece of mantle tissue from a sacrificial oyster was inserted into the
body or mantle of the oyster, that led to the development of a pearl sac
around the nucleus, leading to the deposition of nacre around the
nucleus that formed a spherical pearl. A great breakthrough in Japan's
pearl industry, the method led to the establishment of several cultured
pearl farms in the 1920s, and by 1935 there were 350 pearl farms in
Japan, that produced 10 million cultured pearls annually.
Keshi pearls a by
product of the Akoya cultured pearl industry
As the cultured pearl industry in Japan developed,
pearl farmers engaged in the industry often noticed, that while
harvesting their products after the stipulated grow out period, small
seed-like pearls had developed in pearl sacs adjacent to the nucleated
pearl. Often several of these seed pearls were found in a single oyster.
These seed pearls were found to be made of nacre only, and in that
respect resembled natural pearls, and had a luster surpassing that of
cultured pearls. Such seed pearls made of nacre only and formed as a by
product of culturing Akoya pearls came to be known as "keshi" pearls.
Some properties of "keshi"
pearls
The size of the
pearls
As the name indicates "keshi" pearls are like
natural seed pearls, smaller in size, generally having a diameter of
less than 2 mm. However, this size range applies only to "keshi" pearls
produced by the oyster species Pinctada fucata martensii. "Keshi" pearls
produced by other saltwater oyster species, such as Pinctada maxima
(silver/gold lipped oyster) and Pinctada margaritifera (black-lipped
oyster) have sizes larger than 2 mm, reaching a maximum of over 10 mm.
This is because these oysters produce much bigger cultured pearls than Akoya cultured pearls, that range in size from 8 to 20 mm. Pinctada
maxima produces the largest cultured pearls in the world.
Black Tahiti Keshi Pearls
Photo above, Creative Commons
Shape of the
pearls
Keshi pearls occur in a variety of shapes, but are
mostly irregular or baroque shaped, unlike bead-nucleated pearls which
have regular shapes. In the absence of a bead to guide the final shape
of the pearl, "keshi" pearls can assume a variety of shapes, but
are mostly irregular or baroque.
Strands of different kinds of Keshi Pearls
Luster and orient
of the pearls
Being composed of almost 100% nacre, "keshi" pearls
have a high luster and orient (iridescence) that even exceeds the
highest quality cultured pearls. Luster and orient are reflective and
refractive properties respectively dependant on the thickness of the
nacre. While luster is caused by reflection of light from the surface
layers of the nacre, orient or iridescence is caused by refraction and
total internal reflection of light as it passes through successive
layers of aragonite in the nacre.
Color of the
pearls
Keshi pearls are found in a wide range of colors
depending on the species from which the pearl originated, and the place
of origin of the pearl if they are from the same species. Keshi pearls
from Akoya pearl oysters have the colors in which Akoya pearls usually
appear, such as white and cream, with overtone colors of rose and
silver, but most often the pearls are grayish in color. Those originating from South Sea pearl oyster, the silver-lipped
variety Pinctada maxima, can form pearls of colors, such as
silver-white, silver-pink, silver-gray, bluish-white, cream and yellow.
Golden colored pearls are characteristic of the gold-lipped pearl
oyster. Common colors found in Australian keshi pearls are bluish-white
and silver-gray, and in Indonesian and Philippine keshi pearls are
cream-white and yellow. Keshi pearls formed from the black-lipped pearl
oyster, Pinctada margaritifera are usually pure black or gray in color,
or black combined with overtone colors such as purple, blue, green and
golden or gray combined with overtone colors such as yellow, purple and
green.
The popularity of
"keshi" pearls
The combined properties of "keshi" pearls being made
of nacre only, their extraordinary luster and orient, and the variety of
irregular shapes (baroque) and colors in which they occur, have made
these pearls popular among jewelry manufacturers, who would like to
design something unique and innovative, and the consumers, who would
like to wear such new creations.
Scientific research
reveals the possible causes of formation of "keshi" pearls
The development of "keshi" pearls inside the Akoya
pearl oysters was disadvantageous to the pearl culturists, as the energy
of the oysters was expended in forming unwanted seed pearls instead of
the intended bead-nucleated pearl. If at all a bead-nucleated pearl was
produced it was very small indeed. But, invariably the oyster rejected
the implanted bead, and instead developed "keshi" pearls.
Scientific research carried out to determine the
various causes of development of "kesh" pearls have identified three
possible reasons for the formation of "keshi" pearls.
1) The first possible cause was the tendency of the
pearl oyster to reject the implanted bead nucleus, but not the
accompanying foreign mantle tissue. The mantle tissue either became the
nucleus around which a pearl sac was developed forming a single "keshi"
pearl or fragmented into several pieces which lodged in the soft parts
of the oyster, developing several pearl sacs, forming many "keshi"
pearls.
2) Another possible way was for the bead nucleus to
remain intact without rejection, but tiny fragments of the foreign
mantle tissue, perhaps even single epithelial cells, detach and move to
the other areas in the soft body of the animal, where they develop into
pearl sacs forming "keshi" pearls. The bead-nucleated pearl formed will
however be very small.
3) A third possible reason for the formation of "keshi"
pearls was contamination of the mantle and other interior tissues during
the delicate stage of implantation of the freshwater mussel shell bead
and a fragment of the foreign mantle tissue. The different contaminants
identified are micro- fragments of foreign mantle tissue, and mussel
shell bead, and natural micro-organisms such as parasites. Even tiny
particles of sand have been suggested as possible contaminants. The
irritation caused by these contaminants, lead to the formation of pearl
sacs in which "keshi" pearls develop.
An unexpected demand
from the Indian pearl jewelry industry helped the Japanese pearl farmers
to dispose of the large quantities of unwanted "keshi" pearls
"Keshi" pearls made of nacre only, like natural
pearls, became a much sought after pearl, in a world hungry for the rare
natural pearls that were becoming scarcer and scarcer. Pearl traders
from India, particularly from Hyderabad - "The Pearl City of India," the
center of the pearl industry in India with a history of two
centuries of a vibrant pearl culture, under the patronage of the Nizams
of Hyderabad - realized that the enormous quantities of "keshi" pearls
produced by the pearl farms in Japan, being a 100% nacre-containing
product, with its concomitant brilliant luster, would be an ideal
substitute for natural pearls, to meet the demand for such pearls, and
keep their traditional industry buoyant. Hyderabad had a large workforce
of artisans, skilled in sorting, grading, piercing and stringing pearls.
The drilling of pearls was a highly skilled manual job done with perfect
accuracy in Hyderabad, without damaging the pearls, whose techniques
were a jealously guarded family secret, passed down from generation to
generation. It is the availability of this skilled manpower, that
propelled Hyderabad to the forefront as the main pearl jewelry
manufacturing and trading center in the world today. Low labor costs and
unmatched craftsmanship were two main factors that attracted pearls to
the Hyderabad pearl markets. Thus, the Indian pearl dealers, came to an
agreement with the Japanese pearl farmers to supply the Hyderabad pearl
industry with the by product of their cultured pearl industry, the "keshi"
pearls, that were later set into various pieces of jewelry such as
necklaces, bracelets etc., which eventually entered the jewelry markets
of the Middle East, where there was a great demand for natural pearls.
Intentionally created
"keshi" pearls
When the demand for the "keshi" pearls increased,
some pearl farmers began the practice of deliberately inserting only
mantle tissue with no nucleus into potential pearl-producing Akoya oysters,
that resulted in the production of only keshi pearls. However, these
pearls were actually intentionally created "keshi" pearls, unlike other
"keshi" pearls that were formed spontaneously. The
definition of "keshi" pearls now broadened to include both spontaneously
and intentionally created non-nucleated pearls in saltwater oysters
The technique of
producing non-nucleated freshwater pearls from freshwater mussels was
perfected only in the early 1960s
The Japanese successfully cultured saltwater Akoya
pearls in 1916, and by the 1930s there were 350 Akoya pearl farms
producing millions of Akoya cultured pearls annually. Attempts to
culture freshwater pearls in the freshwater mussel species, Hyriopsis
schelegi found in the lakes of Japan, such as the Lake Biwa, was started
in 1928, by Dr. Masao Fugita and his colleague Yoshida, using the same
techniques developed by Mikimoto, but the results were not so
encouraging, despite the fact that research work was carried out until
the late 1930s. Seiishiro Udo and Keisaburo Sakiyoshi continued
the research work, started by Fugita and Yoshida in 1928, beginning from
1945. Their efforts were successful only in the early 1960s, when Udo
and Sakiyoshi perfected the technique of non-nucleated pearl production
in freshwater mussels
using mantle tissue only. The duo formed the Shinko Pearl Company, the
first company that began the commercial production of freshwater pearls,
that came to be known as Biwa pearls.
The Japanese referred
to non-nucleated freshwater pearls also as "keshi" pearls
Freshwater pearls produced by
mussels being non-nucleated and formed around mantle tissue, like "keshi"
pearls, were also referred to as "keshi" by the Japanese. Thus,
the
Japanese definition of "keshi" pearls included all non-nucleated or
non-beaded pearls, formed around mantle tissue, either spontaneously or
by human intervention, in not only saltwater oysters but also freshwater
mussels. Therefore, Biwa pearls are also a kind of "keshi" pearls
according to this definition. Biwa pearls like saltwater "keshi" pearls
are mostly irregular (baroque) in shape, but can also exist in a variety
of different shapes, such as rounded, near-round, button, oval,
elongated (dogtooth), flat, grain etc. It was also possible to produce
any desired shape, by manipulating the shape of the mantle tissue
implants, such as bars, crosses, sticks, triangles, butterflies,
dragons, letters of the alphabet etc.
The CIBJO restricts
the term "keshi" only to non-nucleated saltwater pearls produced by
saltwater oysters.
The freshwater "keshi" pearls from Japan, being
all-nacre pearls, had an extraordinary luster and iridescence, but not
as high as saltwater "keshi pearls." Thus, after the 1960s, when
freshwater "kesh" pearls, from Japan entered the international pearl
markets, there was considerable resistance to the product, by pearl
importers in consumer countries and their trade associations, who
suggested that the term "keshi" be restricted to saltwater pearls only,
and the use of the term be banned for freshwater pearls. The CIBJO, the
International Jewelry Confederation, accepted this suggestion, and
restricted the use of the term "keshi" only to non-nucleated saltwater
pearls, produced accidentally or intentionally in saltwater oysters.
The controversy
surrounding the nature of "keshi" pearls
Similarities
between "keshi" pearls and natural saltwater pearls
Keshi pearls consist of almost 100% nacre, and are
therefore similar to natural pearls, which too are made exclusively of
nacre. Like natural saltwater pearls, "keshi" pearls have an excellent
luster and orient that surpasses even the highest quality cultured
pearls. The luster and orient (iridescence) of a pearl is closely
related to the amount of nacre deposited in it. Thus, "keshi" pearls
being made of nacre only should have the highest luster and iridescence,
which no doubt these pearls possess.
Another important fact about "keshi" pearls is that
their formation is due to a chance occurrence, like natural pearls. It
is not known in advance which of the bead implanted oysters would form "keshi"
pearls. The formation of "keshi" pearls is invariably a reaction of the
oyster to the implantation of the bead, which is rejected, and the
oyster uses only the foreign mantle tissue to form one or more pearl
sacs that develop the "keshi" pearls. Other instances such as accidental
contamination by the pearl culturist, may still be considered as
cultured pearls.
CIBJO
definition of "keshi" pearls that considers them as non-beaded cultured
pearls
In spite of the fact that "keshi" pearls are all
nacre, and mostly produced by a chance occurrence like natural pearls,
the CIBJO, the French acronym for Confédération Internationale de la
Bijouterie, Joaillerie, Orfèvrerie, des Diamants, Perles et Pierres,
which translates as the International Confederation of Jewelry,
Silverware, Diamonds, Pearls and Stones (normally shortened to the
International Jewelry Confederation), considers "keshi" as cultured
pearls, defining it as a non-beaded cultured pearl, 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 creation results from
the formation of a pearl sac either following injury of the mantle rim
upon handling; from a partial piece of the inserted (transplanted)
mantle tissue; or the whole inserted piece following the rejection of a
bead.
Thus, even though "keshi" pearls have all the
characteristics of natural pearls, they are still considered as cultured
pearls, because they are formed as a by-product of the culturing process
from an oyster that has been subjected to human manipulation.
Expert opinion on
the true nature of "keshi" pearls is divided
In spite of the CIBJO definition of "keshi" pearls
that classifies them as cultured pearls, many gemologists believe that
these pearls are still natural pearls because they are produced
spontaneously. They feel that calling them cultured pearls does not
reflect what actually happens inside the pearl oyster during their
formation. Thus expert opinion is divided as to whether "keshi pearls"
be classified as natural or cultured pearls.
Even if we accept the position that "keshi" pearls
are natural pearls, there is no way of distinguishing a spontaneously
formed "keshi" pearl from a "keshi" pearl developed by human
intervention by implanting only mantle tissue, as some Akoya pearl
culturists did to cater to the Middle Eastern and Indian markets.
Perhaps this was one of the reasons that prompted CIBJO to classify all
"keshi" pearls as cultured pearls.
Arab and Islamic
viewpoint that considers "keshi" as natural pearls
The people of the Arab countries of the Middle East
with an ancient history of harvesting, and processing of natural pearls
for jewelry, from the Persian Gulf, the hub of the natural pearl
industry for several millennia, have a special liking and attachment for
natural pearls. Thus, bead-nucleated saltwater oyster pearls and
tissue-nucleated freshwater mussel pearls and jewelry items produced
with these pearls are not so popular in Arab countries. The idea of wearing pearls that
mollusks were forced to grow was revolting in the Arab mind-set, and
considered unethical in a society practicing a religion that strongly
advocates peace with the natural environment gifted by God. Thus when
the existence of "keshi" pearls was brought to the notice of the Arab
elite, the opinion was expressed that such pearls produced as a
by-product of saltwater pearl culturing were indeed natural pearls, a
viewpoint that gained general acceptance. The reasons advanced for such
an opinion was that keshi pearls were formed as a result of a chance
occurrence as natural pearls in nature, even though they were produced
in oysters manipulated by human beings. A second reason advanced to
support this viewpoint, was that in most cases "keshis" were produced as
a result of the mollusk going against the wishes of man, rejecting the
nucleus he had implanted, and instead using only the mantle tissue to
form one or more pearl sacs that produce "keshi" pearls. In other words
"keshi" pearls are the ultimate result of the oyster taking control of
its own god-given abilities, running counter to man's own intentions. A
sort of rejection of man's intervention to take control of the oyster's
pearl producing mechanism.
China's freshwater
pearl industry
The initial
production of freshwater pearls in China in the 1970s and 1980s were of
low quality known as "rice crispy pearls"
After Japan successfully cultured freshwater pearls
from freshwater mussels in the early 1960s, the Chinese too experimented
with the techniques of producing freshwater pearls, and took the gem
world by surprise in 1968, when they flooded the markets with large
amounts of inexpensive cultured freshwater pearls. However, the pearls
were of low quality and came to be known as "rice crispy pearls" and
were not well received. The species of freshwater mussel used for
culturing "rice crispy pearls" was Cristaria plicata, commonly known as
the Cockscomb pearl mussel. Chinese pearl culturists performed multiple
grafting of up to 50 grafts per mussel shell, which is 25 grafts per
valve. After the valve of a 6-12 month old mussel is opened tiny
incisions are made on the mantle tissue and 3 mm square pieces of mantle
tissue from a donor mussel are introduced into these incisions, twisting
the tissue slightly, to round up the edges. When grafting on one side of
the mantle tissue is completed, the valve on that side is closed, and
the process is repeated on the other side of the mantle tissue. The
grafted mollusks are then returned to their natural freshwater
environment, where they are tended for 2-6 yeaars. Production of rice
crispy pearls continued during the 1970s and 1980s.
Dramatic increase
in quality of pearls produced by China, after the introduction of a new
mussel species, and reduction in the number of grafts
However, in the 1990s Chinese researches introduced a
new freshwater mussel for pearl production, known as Hyriopsis cumingi,
commonly known as the triangle shell mussel. Researches also reduced the
number of grafts to 12-16 per valve, giving a total of 24-32 grafts for
the whole shell. The change in the species of mollusk and the reduction
in the number of grafts had a dramatic effect on the quality of the
pearls produced. Further improvement in quality and variety of colors of
Chinese freshwater pearls were achieved at the turn of the century, by
the introduction of hybridized mussels, such as the hybrid of Hyriopsis
cumingi with Hyriopsis schlegeli. By the year 2006 China had achieved a
total production of 1,500 tons of freshwater pearls annually, thus
dominating the freshwater pearl industry in the world. The freshwater
pearl industry in China is mainly concentrated in the coastal province
of Zhejiang, which is located in the delta of the Yangtse River in
Southern China.
The Chinese use
the term "keshi" only for second and third generation freshwater pearls
The first harvest of freshwater pearls taken from
mantle tissue grafted mussels, after a period of 2-6 years, were plump
and full-shaped, as they were products of younger mussels showing
vigorous growth, with nacre production at its maximum. Since mussels
have a long life span, healthy mussels can be used to obtain a second or
even third harvest of cultured pearls. After obtaining the first harvest
of pearls, exercising precautions to prevent injuries to the mussel, the
valves are closed, and the mussels returned to the freshwater
environment for a further grow out period. There is no need for a
further implantation of mantle tissue. The mussels can now produce a
second and third crop of pearls, without any implantation, but the
amount of nacre produced decreases with age, and the pearls produced are
flat and thin with concavities and of different shapes. The Chinese
refer to the second and third harvest pearls as "keshi" pearls, but do
not use this term for the first harvest pearls which are plump and full
with the desired shapes. Thus, while the Japanese use the term "keshi"
for all non-nucleated pearls irrespective of the generation and
environment in which they are produced, the Chinese restrict the term "keshi"
only to second and third generation freshwater pearls.
Chinese Freshwater Keshi Pearls
Chinese freshwater flat Keshi Pearls
Why South Sea and
Black Tahitian "keshi" pearls are becoming scarcer ?
"Keshi" pearls and jewelry pieces turned out of them,
were once very popular and could be purchased at a bargain. However,
these pearls are now becoming rarer and rarer. This is mainly because
pearl culturists of the South Sea pearl farms such as in Australia,
Philippines and Indonesia, and the Tahitian pearl farms of the South
Pacific, have now resorted to X-raying the seeded pearl oysters to make
sure that the implanted bead nuclei have not been rejected. If the
nucleus has been rejected, the oyster is again opened up and
re-nucleated, before a keshi pearl is formed. A second attempt in
nucleating an oyster is usually successful. In the case of South Sea
pearl oysters and Black Tahitian pearl oysters, attempting a second
nucleation is advantageous given the long time required for pearl
formation which varies from 2 to 4 years, and the much higher prices
realized for the bead nucleated cultured pearls than "keshi" pearls.
Thus South Sea and Black Tahitian "keshi" pearls are now becoming very
scarce. However, X-raying and re-seeding is not practiced for Akoya
pearls, which are relatively cheaper, and whose grow out period is a
maximum of two years, and the keshi pearls formed have a ready market in
India and the Middle East
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)
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References :-
1) Keshi Pearls - www.pearl-guide.com
2) Keshi Pearls - David Federman. www.modernjeweler.com
3) Keshi Pearls - From Wikipedia, the free
encyclopedia
4) What are "keshi" pearls - www.galttech.com
5) Keshi and Nucleated Freshwater Pearls -
www.pearls.com
6) Keshi Pearls -
www.allaboutpearl.com
7) Cultured freshwater pearls - From Wikipedia, the
free encyclopedia
8) China's Pearl Industry - Stina Bjorkell, February
13, 2008. www.radio86.co.uk
