How Are Pearls Formed?
Other People Are Reading
-
Introduction
-
Pearls have been among the most prized gems throughout history. They were thought by some to be the tears of mermaids----one example of many legends featuring pearls. Unlike most gems, pearls are produced by biological processes, rather than geological ones (as are diamonds or emeralds). A pearl is composed primarily of calcium carbonate in the form of nacre, a substance secreted by oysters and other mussels. A pearl is actually an oyster's attempt to protect itself from irritating particles by coating them with nacre. There are few wild pearls harvested today, because pollution and over-harvesting have taken a toll on natural oyster beds. Most pearls now are cultured, produced in fresh- and saltwater pearl farms. They are considered equal in quality to natural (wild) pearls.
Building a Pearl
-
Oysters constantly strain water to extract nutrients. Sometimes, a particle of unwanted material becomes lodged between the oyster's mantle and its outer shell. The mantle is the part of the oyster that produces nacre, the raw material that produces the oyster's shell as it grows. The oyster responds by coating the irritant with nacre, and so the process of building a pearl begins. Over time, layer after layer of nacre is added, producing a pearl. Different species of oysters tend to produce different shapes and colors of pearls. Round and drop-shaped pearls are the most valuable, especially the black and gold pearls of the South Seas. Pearls in the shape of ovals and buttons are common as well. Other colors range from the iridescent white to gray, blue, green and pink.
-
Cultured Pearls
-
Cultured pearls are the same as wild pearls, except that the pearl forms as a result of human intervention. A pearl farmer opens the oyster's shell and makes a tiny incision in the mantle. A particle (typically a bit of oyster shell) is inserted. The oyster does the rest. Not every oyster that is stimulated to form pearls in this way will yield a valuable gem. Half will not survive long enough, due to predators and other hazards in their environment, despite being kept in nets by pearl farmers. Many that do survive don't form pearls with a shape, color or luster that has market value. But when a high-quality pearl does form, it is a finished product. Unlike mineral gems, it does not need to be cut or polished. When you look at pearl jewelry, what you see is the pearl's natural appearance.
-
Resources
- Photo Credit Photo by Bruno Menetier
