The precious stone that is created by an animal
The pearl is one of the most popular of all precious gems. It is the only one created by a living creature. Its softly shining beauty has made the word the “pearl” mean almost the same thing to us as “beauty” and “great worth. The Bible speaks of ”throwing pearls before swine” and declares the value of worthy wife to be “far beyond pearls”.
Pearls are made by certain kinds of oysters, clams and mussels all of which are shellfish. All these are animals are called mollusks, from a Latin word meaning “soft”, because they have soft bodies inside their hard shells.
The pearl is actually made of the material in the shell with which a mollusk covers a particle that incidentally gets into the shell. The particle may be a piece of broken shell, a parasite, or even a tiny grain of sand. The material with which the mollusk covers are particle is called nacre or mother-of-pearl. As many layers of nacre, which keep covering the particle, are built up, a pearl is made.
Natural pearls are rarely found and large natural pearls even more rarely. Only a few of pearls that are casually found are good enough to be considered valuable.
A valuable pearl ha a beautiful shining luster. Jewelers call the luster the “orient” of the pearl. The luster comes from the inner part of the gem below its surface. It is caused by light that is received by the nacre and then reflected through the layers of the pearl. You see the luster shinning with various colors of light just like those reflected and refracted (broken up) by a glass prism. The value of pearl is also judged by its color and shape.
The color of a pearl is decided by type of oyster, the salt content of the water, the depth of the water at which the oyster live, and temperature of the water. Pearls are usually white, cream, pink or rose, blue-gray or black. White is generally popular and pink is greatly in demand also. Black pearls are highly valued because of their rarity.
The round pearl has the shape that is most desired. To become round a pearl must develop in the soft parts of the mollusk. When a pearl becomes attached to the inside of the shell, it becomes button pearl, rounded on one side and flat on the other. If a parasite tries to get in through the shell, the mollusk will protect itself by covering the spot with extra layers of nacre. This builds up into a blister pearl.
Not every pearl that is formed is valuable. Many pearls are not so attractive. Only those shellfish whose shells are coasted on inside with color-full nacre can produce precious pearls. The most beautiful and costly pearls are especially those formed by pinctada, a pearl oyster that lives in the warm waters of tropical seas. The pearls in edible clams and oysters are usually of poor quality and have no value.
More natural pearls come from Arabian coast of the Persian Gulf. This has been the most famous source of natural pearls for over 2.000 years. Beautiful white and silvery pearls come from the Gulf of Mannar in Ceylon. Fine black pearls come from the west coast area of Mexico and the United States. Pearls are also found near Australia, some island of the South of Pacific, Venezuela and the Pearl Islands near the Panama Canal. Natural salt water pearl are usually gathered by divers.
In many of the rivers and freshwater lakes of the United States, especially in the valley of upper Mississippi, there are many freshwater pearls. The mollusk found in these waters produce pearls that are often very attractive.
Hundreds of years ago Chinese discovered that an object would be covered with nacre if it was placed inside the shell of a calm or oyster. After making experiments that started in the late 1800’s, some Japanese researchers learned how to treat oysters to produce “cultured” pearls at a relatively low cost. Cultured-pearl- production is now a large industry in Japan.
To produce a cultured pearl, a smooth, round piece of nacre is skillfully set into the living tissue of pearl oyster. Then the oyster is returned to the water for 3 to 5 years. The cultured pearls that are produced are cheaper than natural ones, but only expert jeweler can tell the difference between them.
The oysters are gathered by divers. In Japan the divers are women who are trained as pearl divers from childhood. They wear long- sleeved white cotton dresses that cover their bodies from neck to knee. White is worn because they believe that anything white will frighten away sharks. A diver also wears a diving mask that covers her eyes and nose. A rope is tied round the diver’s waist, and the other end of it is tied to a wooden bucket. The bucket holds the oysters and is also used as a float for diver to rest on. Each dive lasts from 25 to 45 seconds.
Once gathered, the oysters are taken to pearl “farms” where they are cleaned and selected according to their age, size and health.
13 June 2017