How does a pearl form

Although many pearls can be produced by man, natural pearls are the most sought after and expensive form of pearls. The most cherished pearls are created by oysters. Unfortunately, not all oysters could produce pearls, so the natural pearls are extremely rare and precious. Now here are the introduction about how does a pearl form.
When a speck of sand drop into the oysters' shell, the oyster will defense to cover the sand with the few things it'd body produces. It covers the sand all over. As upon layer of nacre is added, the object becomes larger and a pearl is formed.
With the development of science, human could have intervention in pearl form, by farming, or cultivating pearls. In these ways, human has a more control on pearl formation. The pearl farming has given us cultured pearls. Cultured pearls are produced by pearl oysters with the technique developed by scientists. In the process, the humans play important role, providing suitable environmental conditions for the pearl oysters. Good pearls are the result of careful selection.
The quality of pearls, with the pearl shapes and pearl colors, are important factors for the pearl price. All these are not only influenced by external environment, but also by the inherited capabilities of individual oysters.
If you interest in pearls, you can found the information useful. And you can share these with your friends who love to buy pearls.