Pearl
Hardness 3.5-4.5 specific gravity 2.60-2.78
Pearl luster
Wear: easy to wear and avoid acid substances
Pearl is the oldest organic gem used by human beings. It is produced in mollusks, such as oysters, mussels and other Bivalvia animals.
"Pearl" has a special "pearl luster", which is formed by the diffraction of the lamellar crystal edge of the nacreous layer. The colors of pearls include white, pink, yellow, gray, purple, black, etc.
Before 1900, almost all "pearls" were natural pearls. In 1905, Japanese Kokichi Mikimoto successfully cultivated "pearls" on a large scale. At present, most of the pearls traded in the world are "cultured pearls".
Pearl is a June birthstone.
The history of human understanding of "Pearl"
In prehistoric times, when there were no words or records, people had found "pearls" in oysters when they were searching for food by the sea. This kind of gem does not need any polishing or cutting, it presents beautiful luster, so it is valued and praised in many ancient civilizations.
The ancient Egyptians regarded "Pearl" as an important burial gem; the ancient Romans regarded "Pearl" as the ultimate symbol of wealth and social status; the Greeks associated "Pearl" with love and marriage. In the middle ages, every European noblewoman wanted to have a pearl necklace, and knights often wore pearls to fight for good luck.
During the period of European colonization to the new world, the Europeans found pearls in the sea area of Central America and became an important source of wealth. Over exploitation led to the depletion of almost all American pearl oyster populations in the 17th century.
Before the 1900s, pearls were only precious stones owned by the upper class. In 1916, Jacques Cartier, a French jeweler, traded two pearl necklaces for Cartier's shop on Fifth Avenue in New York City. The two necklaces had 55 and 73 natural pearls respectively, which were worth $1 million at that time.
The formation of "Pearl"
The most important pearl producing mollusks are oysters (oysters) and mussels (mussels). When foreign bodies enter the bodies of these two mollusks, their specific epithelial cells secrete calcium carbonate and nacre to enclose the foreign matters. The nacre consists of calcium carbonate (CaCO3) and a small amount of organic matter (protein). The calcium carbonate is in an oblique direction The crystal system is composed of aragonite crystals.
"Marine pearl" often adopts "nuclear culture". First, choose healthy oysters, and implant one or more "pearl beads" and "mantle tissue" in the oysters. These pearl beads are often made of oyster shells, and "mantle tissue" is cut from the mantle of other oysters. It usually takes 2-3 years for the living oysters to be cultured in water.
Fresh water pearl often adopts the "non nuclear culture" method, and directly implants the "mantle tissue" of other mussels in the healthy mussels. The growth of Pearl usually takes about 2 years. There are small and irregular holes in the center of cultured pearls.
Varieties and important producing areas of "Pearl"
The important varieties of "sea pearl" include "Akoya pearl" from Japan, "South Sea cultured pearls" from the Pacific region, "Tahiti cultured pearls" from Tahiti and Cook Island.
Judgment on the value of "Pearl"
The value of pearls is influenced by many elements such as luster, color, shape and size. The thicker the pearl layer, the stronger the luster. The best round pearl is called "walking plate pearl".
Pearls have a special unit of weight called "grains". 1 pearl grain = 1 / 4 Carat or 0.05g.
Wearing and maintenance of "Pearl"
The hardness of "Pearl" is only about 3. Wear it to avoid wear of hard objects.
"Pearl" is very vulnerable to erosion, such as detergents, soap, hair spray, perfume, alcohol and so on will damage the Pearl. If you need perfume, you should first spray perfume and then wear pearls to avoid spraying perfume directly on the Pearl.
"Pearl" should avoid high temperature and over drying. Exposure to the sun and high temperature drying may lead to dehydration and cracks.
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