Portal:Gemology and Jewelry/Selected article/5

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A pearl is a hard, rounded object produced by certain animals, primarily mollusks such as pearl oysters. Pearls can be used in jewelry and also crushed in cosmetics or paint formulations. Pearl is valued as a gemstone and is cultivated or harvested for jewelry. The unique luster of pearls depends upon the reflection and refraction of light from the translucent layers and is finer in proportion as the layers become thinner and more numerous. The iridescence that some pearls display is caused by the overlapping of successive layers, which breaks up light falling on the surface. Pearls are usually white, sometimes with a creamy or pinkish tinge, but may be tinted with yellow, green, blue, brown, purple, or black.

Before the beginning of the 20th Century, pearl hunting was the most common way of harvesting pearls. Now, however, almost all pearls used for jewelry are cultured by planting a core or nucleus into pearl oysters. The largest pearl ever found so far, came from the Philippines in 1934. It weighed 14 lb (6.4 kg) when it was discovered by an anonymous Filipino Muslim diver off the island of Palawan.