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Natural pearls are those which are formed in nature,
more or less by chance. Cultured pearls by contrast, are those in
which humans take a helping hand. The only difference is that in the
one case, the process was begun accidentally; while in the other case,
it was begun intentionally.
The technique of producing spherical cultured pearls was developed in
Japan, and the culturing of pearls is a major industry today in many
parts of Asia, including China, Thailand, and the South Seas of
Tahiti. Artificial pearls, in contrast to cultured pearls, are
entirely artificial made largely of glass.
Pearls have been cultured successfully since 1920. In this process a
mother-of-pearl bead, from three-quarters to nine-tenths of the
diameter of the desired product, is introduced into the the tissue of
a pearl oyster. Over a period of years the oyster secretes layers of
nacre around the bead. As the nacre builds up in layers, it surrounds
the irritant and eventually forms a pearl. Cultured pearls are not
easily distinguished from natural pearls except by an expert.
Modern-day cultured pearls are primarily the result of discoveries
made in the late 19th and early 20th centuries by Japanese
researchers, most notably Kokichi Mikimoto. What Mikimoto discovered
was a specific technique for inducing the creation of a round pearl
within the tissue of an oyster.
This discovery revolutionized the pearl industry, because it allowed
pearl farmers to reliably cultivate large numbers of high-quality
pearls. In contrast to natural pearls, which have widely varying
shapes, sizes, and qualities, and which are difficult to find. The
pearls can be grown by the tens of thousands, thereby bringing their
cost down to a point where cultured pearls became accessible to large
numbers of people around the world.
Cultured pearls can often be distinguished from natural
pearls through the use of xrays, which reveals the inner nucleus of
the pearl.
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