| Publish Date: Friday,17 October, 2008, at 01:30 AM Doha Time |
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| Dr Hubert Bari |
These were just some of the fascinating facts revealed by Dr Hubert Bari, the curator of gems and jewellery at the Museum of Islamic Art, at the opening meeting of the Qatar Natural History Group’s new season on Wednesday.
Almost 200 members turned up to hear Dr Bari endeavouring to dispel the fantasies surrounding the subject of pearls and reveal the reality.
For many centuries, he said, there was a popular belief that pearls formed when the oysters rose to the surface and opened their shells to receive drops of dew or rain. In the 20th century most people believed in the sand grain theory. The truth is far more prosaic. Pearls are formed when tiny worms bore into the shell of the oyster, and the irritation causes the shellfish to excrete a liquid which hardens into pearl. Worms and even small fish are occasionally found inside oyster shells, entombed in a shining pearl casing.
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| A pearl embedded on the edge of the valve in a Periglypta magnifica found in the Philippines. The shell measures 10 cm in diameter. Qatar Museums Authority’s collection |
Pearl dealers tend to conceal the origins of this type of pearl from their customers, observed Dr Bari, fearing it might put them off buying!
Another popular belief is that only pearl oysters produce pearls. But in fact all bivalves, gastropods, cephalopods such as octopus, squid and cuttlefish and even land snails are capable of forming pearls. Some of the world’s rarest and most valuable pearls come, not from oysters, but from a variety of these creatures.
Pearls from the Arabian Gulf obtain their softly glowing lustre from a mineral called argonite, which forms flat platelets of crystal that reflect light. Even rarer are the pearls from a shellfish named Nautilus pompilius, found in the Philippines, in which fibres of calcite produce an extraordinary light effect called ‘flames’.
Pearls obtain their range of colours not only from the colour of the shell but from the position of the pearl within it. Highly-prized pink pearls come from conch shells, once found by the thousand in shallow Caribbean waters until by the 1970s relentless over-fishing drastically reduced their numbers, so that today divers have to seek them in deep water far from the shore.
Another common misconception dispelled by the speaker is that a method of making cultured pearls was first invented in Japan. In fact, said Dr Bari, it is known that cultured pearls were being produced in China hundreds of years ago. In 1761 a Swede, Carl von Lime, successfully produced cultured pearls but failed to take out a patent.
Today, there are many methods of encouraging oysters to form pearls, ranging from the insertion of a tiny bead within the shell to delicately snipping off a minute piece of the outer mantle of the shellfish and inserting it deep into the flesh. 95% of the pearls on the market today come from China, most of them from freshwater mussels.
Many of the photographs of rare and beautiful pearls shown by Dr Bari to his audience are of pearls in what he claims is the finest collection in the world, recently purchased by Qatar Museums Authority. Next year, hopefully, the collection will go on public display, one of many acquisitions of marvellous and unique treasures which Qatar is building up for eventual display in a range of world-class museums.