The mantle of mussels is stimulated by the invasion of foreign bodies (sand and parasites). The epidermal cells in the stimulation area take foreign bodies as the core and fall into the connective tissue of the mantle. Some of the trapped epidermal cells divide themselves to form nacre, which secretes nacre and the nucleus is wrapped layer by layer to form pearl. Pearls with foreign bodies as the core are called "nucleated pearls".
After pathological stimulation, a part of the outer skin of the mantle undergoes cell division, and then it is separated, coated with organic substances secreted by itself, and gradually falls into the connective tissue of the mantle, forming pearl sacs, and then forming pearls. Because there is no foreign body as the core, it is called "seedless pearl".
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Pearl has always been loved by people for its warmth, elegance and splendor, and is known as the queen of jewelry. The composition of pearl is calcium carbonate containing mechanism, which has poor chemical stability and can be dissolved in acid and alkali. It is not advisable to touch perfume, oil, salt, alcohol, hair cream, vinegar and dirt in daily life. But also can't contact with organic solvents such as banana oil.
People sweat a lot in summer, so it is not advisable to wear pearl necklaces. When not in use, wipe it with a soft, slightly wet clean cotton cloth and dry it for storage. Don't use any detergent to clean them. Don't expose or bake in the sun; When collecting, you can't use mothballs, and don't put them in the bank vault for a long time.
The hardness of pearls is very low. White pearls that have been worn for a long time will turn yellow and their luster will become worse. They can be bleached with 1%- 1.5% hydrogen peroxide. Be careful not to bleach excessively, otherwise it will lose its luster.
Baidu Encyclopedia-Pearl