Fellow Orchideans- I have a question: Can someone explain the grooves
you sometimes see running around the diameter of pearls? I’ve seen
them in south sea Tahitian pearls, I’ve seen them at the other end of
the spectrum in less expensive Chinese pearls- sometimes the grooves
are deep, sometimes there are multiple grooves- not so deep. They
usually run all the way around the pearl. I’m wondering how they
form…actually one of the boutique owners who sells our jewelry is
wondering.
Dear Kate, The rings you are seeing are growth rings. Since
freshwater pearls are tissue nucleated, the bulk of the pearls being
pearl nacre, they may grow at fits and spurts and create the rings.
Saltwater pearls being bead nucleated will seldom have them as the
nacrous coating is thin over the perfectly round bead. Hope this
helps! Suzanne
ps. If you have a good library nearby, you may get alot of
reading Fred Ward’s book on pearls. About $16.00 if you
decide to buy a copy.
Can someone explain the grooves you sometimes see running around the diameter of pearls?
Hi Kate, They’re marketed as “circle pearls.” Some smart cookie
realized that you could make them more desirable by imaging them as
symbols of eternity; it’s sort of like calling brown diamonds
“champagne diamonds.”
The grooves or circles are actually imperfections in light of the
fact that the industry considers the “perfect” pearl to be absolutely
round. Off-rounds (ovals), baroques (irregular/knobby), circle pearls
– all are considered “imperfect.” I use the quotes because, for my
taste, the perfectly round pearl is somewhat boring compared to the
“imperfect” ones; nevertheless, it is the most prized and will carry
the highest price.
I’m not sure anyone knows specifically how a circle pearl or other
baroque forms. Apparently something causes the oyster to form an
irregular layer of nacre – perhaps a change in temperature or a
particularly strong tide or some kind of irritant (I’m guessing
here). Whatever it may be, I for one am grateful for the
interruption of the process; otherwise they’d all be “perfect”
pearls.
Beth
Actually, a large portion of Tahitian pearls do have rings, Suzanne.
I can’t speak for South Seas or Akoyas, but I suspect at least the
South Seas to be similar since it is a closely related species of
oyster to the Tahitian black-lipped oyster.
JoAnna Kelleher
Pearl Exotics Trading Company
Hi Suzanne,
Since freshwater pearls are tissue nucleated . . .
Some freshwater pearls are tissue-nucleated; others are
bead-nucleated. In fact the subject of fresh-water pearl nucleation
has been hotly debated of late, since the Chinese are growing such
large, round pearls and claiming they are tissue-nucleated, which
some experts believe to be impossible. These experts say that what
makes a round pearl round is the shape of the bead that’s inserted
and around which the oyster deposits nacre. In fact, some of the
Chinese fresh water pearls have been found to be nucleated with other
pearls – presumably imperfect/low value ones that have been ground
down – rather than with shell beads. These pearl-nucleated pearls,
since they are composed of all nacre, appear to have no nuclei.
Other examples when examined, however, do seem to have no perceptible
nucleus. The conclusion seems to be that pearl manufacturers will
use any and every method at hand to produce a high luster, large
round pearl as quickly as possible.
Saltwater pearls being bead nucleated will seldom have [growth rings], as the nacrous coating is thin over the perfectly round bead.
There are plenty of salt-water circle pearls around! I see them all
the time – in black Tahitians, for instance. As for the nacreous
coating of a salt water pearl, yes it would be thinner than the nacre
of a tissue-nucleated pearl but patently not too thin to produce
circles.
Beth
I'm not sure anyone knows specifically how a circle pearl or other baroque forms. Apparently something causes the oyster to form an irregular layer of nacre -- perhaps a change in temperature or a particularly strong tide or some kind of irritant (I'm guessing here)
It seems to me that I have read somewhere that it is the movement
of the pearl inside the oyster in a rotational fashion, with a part
of the animal not laying nacre as well as the rest, thus the odd shapes.