Akoya oysters are now grown in hatcheries to
insure a constant supply. The oysters
are fed a grown microscopic organism called plankton. A few months into their growth period the
oysters are moved from the hatcheries to the cultivating areas where they are
monitored and fed until they are strong enough to withstand the nucleating
operation. In the operation,
a technician inserts a shell bead nucleus together with a piece of mantle from
a donor oyster into the mollusk’s gonad area. This piece of mantle forms a sac over the nucleus and the sac secretes
nacre over the bead nucleus. This
secretion will eventually lead to a cultured pearl.
Oysters that have been
operated on are then suspended from rafts in the water for a period of time
ranging from eight months to two years.During the time they are in the water they are moved from warmer to
colder water.This is very important in
the development of Japanese Akoya pearls.More nacre is secreted in warmer water than in colder water.But, the nacre that is secreted in colder
water is the nacre that gives the pearls their mirror like luster.
Chinese Akoya pearls that are grown completely in
warmer waters might have a thicker nacre coating but do not have the luster of
Japanese cultured pearls.
Southern China Hainan Zhejiang where Chinese Akoya are cultured.
The suspended oysters are
periodically scraped to remove barnacles and opened to check the growth of the
pearls.Some of the oysters die or
reject the nucleus.These oysters are
removed to allow more nutrition for the survivors.If during these checks the cultivator sees
that the pearls are developing well in many of the oysters he will decide to
leave a certain percentage of the oysters in the water for another growing
season.This is called the “second
growth”.It allows the pearls to have a
thicker nacre coating and a higher luster than those oysters left in the water
for one growing season.
The oysters are harvested in
December and January and opened to remove the pearls.The pearls are then placed in a tumbler with
salt and water which gently polishes them.The pearls are then brought to auctions which are held in the
cultivating areas and the highest bidder above the floor price will be the
winner.
The people who buy the pearls
at auction are called processors.They
take the pearls, polish them some more, bleach them so that they become whiter
and sometimes tint them to increase the body color of the pearls.
They are then divided into different sizes and
shapes and qualities.Those pearls which
have the highest luster and are the roundest and have the fewest surface
imperfections are the most valuable.The
pearls are then divided into those to be used for necklaces and those to be
used in jewelry.The pearls selected for
necklace are drilled thru and those to be used in jewelry are drilled half way
thru and called half-drilled pearls.
In
the early 1950's when cultured pearls were becoming popular the
quantity available was much less then today. Most of the necklaces
produced then were graduated and ranged in size from 3MM to 71/2MM and
were called 31/2 momme grads. This description referred to the weight
of the necklace in momme, a weight measurement used by the Japanese. A
momme is equal to 18.75 carats. As more pearls were produced uniform
necklaces became popular and remain the most popular today. A uniform
necklace is one in which there is a half millimeter difference between
the center pearl and the end pearl in the necklace, the center pearl
being the larger.
