torsdag 23. februar 2012
What Makes Freshwater Pearls Different?
Freshwater pearls
differ from other cultured pearls, in that the great majority of them
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, then 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 is really just
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 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 perfectly round.
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