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Myth and reality about pearls
“Pearls,” the second temporary exhibition at Museum of Islamic Art has brought forth evidences to prove many of the long – held facts about pearls wrong.
For long, people have believed that the pearls are formed around grains of sands. It is also a common belief that pearls can be produced only by few oysters only. Some also believe that pearl can never be tampered by nature.
The exhibition has showcased artifacts that shatter these ideas. Among the exhibits are two mollusks shells which have an embedded fish and worm becoming pearls.
A pearl is formed due to injuries in the soft tissue producing the shell material. Cause is mostly a little parasite. Most of pearls arise from the intrusion of a parasite in a seashell. The parasite can, while progressing, damage the ‘mantle’, the organ producing the shell material. The parasite can transfer the cells that produce the shell into the internal flesh of the animal. These lost cells will proliferate, forming a cyst, and will produce the shell substance in the middle of the flesh and a pearl is then formed.
Also proving these facts are the segments of pearls which shows that there are no grain of sand. It has only concentric layers of calcium carbonate, the main component of the pearls.
Pearls usually are round or have smooth curves because of its continuous rotation during its formation. The oysters rotate the pearls to make it as round as possible because it is less harmful than a pearl with rough angles.
The main component of pearl is calcium carbonate up to 92 percent, along with water and an organic substance similar to human fingernails: conchiolin. These water molecules are strongly bonded and evaporate only above 120°C.
However, overtime, the pearls can dehydrate and crack. Since the colours in pearls are due to organic compounds, as melanin in black pearls, it can fade as a result of long exposure to sunlight.
MIA has exhibited various types of shells and a whole new variety of pearls from them. All shells can form pearls, including the land snail French delicacy and can be found all around the world, up to the polar circle. From porcelain like pearls to the usual ones a number of sample pearls from big clamp shells have been exhibited.
Though it is usually a parasite that leads to pearl formation, this accident is very rare. In the Arabian Gulf, around 2000 oysters had to be opened in order to find a single beautiful pearl. To discover a rare pink pearl, 20,000 sea snails in the Caribbean had to be fished. Event today, quest for natural pearls poses the problem of the extermination of shellfish, particularly in the Philippines and in Indonesia.
The search for natural pearls today represents a very limited economic activity. They are rare and expensive, and only the finest jewellery features such exotic pearls as the orange pearl of Melo or the pink pearl from the Caribbean. Natural ‘classic’ pearls from pearl oysters are still found, but only a few thousands a year are harvested.
http://www.thepeninsulaqatar.com/Display_news.asp?section=Local_News&month=January2010&file=Local_News201001302620.xml |
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