Obtaining Pearls

A pearl has unforgettably soft nuances of colour, which reach our eyes as iridescent colours. Pearls are considered to be very precious and on a par with the most expensive gems. The translucent, soft glow which gives the pearl its special charm is called the “lustre” or “orient” of the pearl.
Pearls are formed by oyster-like sea molluscs out of mother-of-pearl, the rainbow-coloured material with which the inside of their shells is covered. Sea oysters that produce pearls have a diameter of 8 cm. They reach an age of 13 years, and live in coastal waters up to 15 m deep.
When a foreign body, for instance a grain of sand, enters the shell, the oyster is irritated by it (as when dirt gets in our eye). The kernel may be microscopic in size, but the oyster begins immediately to secrete the organic mother-of-pearl. A series of small calcium crystals then settle around it, upon which in turn a very thin layer of organic matter is deposited. This concentric construction continues until the particle has been so encapsulated by the oyster that it is no longer hindered by the foreign object. In the process a little sphere has been formed – the pearl. It carries the glow of mother-of-pearl. In principle it is the same colours that we find in oil on water or in soap-bubbles.
It has been calculated that the formation of larger pearls can take up to 10 years. Many of the oysters that are found contain no pearl at all, for only one in 30 or 40 produce...

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