Shiyan vs Pearl

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Shiyan (Chinese: 十堰; pinyin: Shíyàn) is a prefecture-level city in northwestern Hubei province, China, bordering Henan to the northeast, Chongqing to the southwest, and Shaanxi to the north and west. At the 2010 census, its population was 3,340,841 of whom 767,920 lived in the built-up urban districts of Maojian and Zhangwan on 1,193 square kilometres (461 square miles).

In 2007, the city was named China's top ten livable cities by Chinese Cities Brand Value Report, which was released at 2007 Beijing Summit of China Cities Forum.

Source: Wikipedia

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A pearl is a hard, glistening object produced within the soft tissue (specifically the mantle) of a living shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pearl is composed of calcium carbonate (mainly aragonite or a mixture of aragonite and calcite) in minute crystalline form, which has deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes, known as baroque pearls, can occur. The finest quality of natural pearls have been highly valued as gemstones and objects of beauty for many centuries. Because of this, pearl has become a metaphor for something rare, fine, admirable and valuable. The most valuable pearls occur spontaneously in the wild, but are extremely rare. These wild pearls are referred to as natural pearls. Cultured or farmed pearls from pearl oysters and freshwater mussels make up the majority of those currently sold.

Imitation pearls are also widely sold in inexpensive jewelry, but the quality of their iridescence is usually very poor and is easily distinguished from that of genuine pearls. Pearls have been harvested and cultivated primarily for use in jewelry, but in the past were also used to adorn clothing. They have also been crushed and used in cosmetics, medicines and paint formulations. Whether wild or cultured, gem-quality pearls are almost always nacreous and iridescent, like the interior of the shell that produces them. However, almost all species of shelled mollusks are capable of producing pearls (technically "calcareous concretions") of lesser shine or less spherical shape. Although these may also be legitimately referred to as "pearls" by gemological labs and also under U.S. Federal Trade Commission rules, and are formed in the same way, most of them have no value except as curiosities.

Source: Wikipedia