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Black pearl is one of the most important species of dark pearl series, high quality pure dark pearl is rare. There is a fairy tale about black pearl: if a drop of dew falls into the sea and happens to drop into the mouth of a seashell, then the dew will turn into a pure pearl. When the weather is bad and the sky is dark, the dew will turn into a black one. This fairy tale began to spread in the 15th century, even everyone knows it today. Although it is unable to explain the cause of black pearl, however, it indicates that people consider black pearl to be particular ornament from their beginning of understanding of pearl. The color of high quality black pearl is mainly peacock green or steel gray. Black one is popular after 1970s. In the ancient time, people could only obtain the natural black one by chance, because of the rare production, no one paid much attention to it. In 1965, Japanese pearl experts successfully carried out Black Lip Shell's cultivating technology, the colors of cultured pearl ranged from green to black, which mean the new page of commercial production. However, the colors of pearl which come from Black Lip Shell are not all black, the precious ones are even less. Currently, there are only two natural birthplaces of black pearl, one is the Tahiti of Polynesian islands, where 95% of pearls are produced around the world. The other is the Penrhyn Island in the Northern Cook Islands with a production of 4%. These two areas are both in South Pacific Ocean, so black pearl is also called South Sea pearl. The amount of high quality black pearl is no more than 15 million, about 40% of them will be sold through the annual international auction. Diameters of most black pearls are around 9mm to 10mm, while about 60% are not over 11mm. So people often consider 11mm to be the boundary, the ones above 15mm with perfect round shape will be fairly rare and invaluable. Most of the South Sea pearls will be made into necklaces, rings and earrings jewelry because of their high value. Reason of the black color: there are two theories telling us what cause the black color, one is the certain minerals and the black microelement such as iron, titanium, vanadium and manganese, the other is the high content of opal in the pearl surface, namely the high content of organic composition and carbonaceous composition. However, no matter how black pearl comes from, there will be no relationship with the anoxic environment, its special color should belong to the special environment.
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