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Although the traditional source of
pearls has been oysters which live in saltwater, mollusks which live
in freshwater lakes and rivers can also produce pearls. China has
harvested freshwater pearls in the form of mabe since the 13th
century, and is now the world's undisputed leader in freshwater pearl
production. The first record mentioning pearls in China was from 2206
BC. The United States was also a major source of natural freshwater
pearls from the discovery of the New World through the 19th century
until over-harvesting and increasing pollution significantly reduced
the number of available pearl-forming mussels.
Generally speaking, freshwater
pearls are not as round as saltwater pearls, and they do not have the
same sharp luster and shine as akoya pearls. However, they appear in a
wide variety of shapes and natural colors, and they tend to be less
expensive than saltwater pearls, making them very popular with younger
people and designers. As
freshwater
pearls are solid nacre, they are also quite durable,
resisting chipping, wear, and degeneration.
With a total production of 1500
tons in 2006, China holds a monopoly over the pearl industry today.
Although the birth of the Chinese freshwater pearl industry is traced
back to the area around Shanghai, freshwater pearls are now produced
in all surrounding provinces including Zhejiang, Anhui, Jiangsu, Hubei,
Hunan, and Jianxi. Local trade is conducted mainly in the cities of
Zhuji (Shanxiahu), Suzhou, Wuxi, Wenling, and Weitang. The largest
market for these pearls in the world's pearl trading hub, Hong Kong.
Freshwater pearls differ from
other
cultured pearls
in that the great majority are not bead-nucleated. Freshwater mollusks
are nucleated by creating a small incision in the fleshy mantle tissue
of a 6 to 12 month old mussel, and inserting a 3mm square piece of
mantle tissue from a donor mussel. Upon insertion the donor (graft)
tissue is twisted slightly, rounding out the edges. What happens after
this point still speculation. Some believe that this tissue acts as a
catalyst in producing a pearl sac thus making the 'nucleation' actual
'activation', others believe the tissue molds with the host to create
a pearl sac, while still others maintain the tissue is the actual
nucleus. Although it is said that a freshwater mollusk can withstand
up to 25 insertions per valve, it is not common industry practice to
perform only 12-16 insertions in either valve, for a total production
of 24-32 pearls. The mollusks are then returned to their freshwater
environment where they are tended for 2-6 years. The resulting pearls
are of solid
nacre,
but without a bead
nucleus
to guide the growth process the pearls are rarely perfect round.
In recent years the Chinese
have been able to take the art of culturing freshwater pearls to new
levels. Although rare, some freshwater pearl production exhibits
luster equivalent to high grade akoya, round shape with less than a
percentage point of deviation, colors as exotic as Tahitian, and size
as large as
South Sea.
Although grades in these category represent much less than 1/10th of 1
percent of total production, due to the enormous production of
freshwater pearls there is a marketable quantity. In recent years
companies like PearlParadise.com have successfully marketed this grade
under the trade name
Freshadama freshwater pearls.
The major shift in quality can
be attributed to several factors. The first being the industry shift
from the Cockscomb pearl mussel (Cristaria plicata) to the Triangle
shell (Hyriopsis cumingii) in the middle 1990's. The Cockscomb was
responsible for the low quality rice-crispy pearls of the 1970's and
1980's. Another shift in quality can be attributed to the lower number
of grafts inserted into either valve. This number has dropped by an
average of 5 per side in the last decade. The turn of the century
brought another wave of quality and exotic
pearl colors
in the form of mussel hybridization.
The
Japanese have a distinguished history of culturing
freshwater pearls as
well. Lake Biwa was once world renowned for producing high-quality
freshwater pearls produced by the Hyriopsis schlegeli (Biwa pearly
mussel) mussel. However, in the mid 1970's
pearl farming
all but came to a halt due to pollution in this lake that was once
synonymous with freshwater pearls. The Japanese tried once again to
farm freshwater pearls in Lake Kasumigaura in the last decade,
utilizing a bead-nucleated hybrid mussel (Hyriopsis Schlegeli
anadonata/plicata hybrid mussels). The resulting pearls have been
quite large and unique. The Kasumiga pearl industry had a very short
life span, however, with production ceasing in 2006. The industry is
once again a pollution fatality of Japanese industry. The remaining
Kasumiga pearls are exclusively sold by the Belpearl pearl company.
... read more on
Pearl Treatments
Information
obtained from www.Pearl-Guide.com
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