Cultured pearl
Cultured pearls are real pearls created through a controlled farming process involving either freshwater mussels or saltwater oysters. Unlike natural pearls, which form spontaneously in the wild, cultured pearls are produced by inserting a small irritant, usually a shell bead, into the mollusk. This prompts the bivalve to secrete nacre, the substance that gives pearls their luster, layering it over the irritant over time. Cultured pearls can vary in shape, size, and color, influenced by the type of oyster used and farming techniques. While freshwater pearls were historically smaller and less desirable, advancements in cultivation have led to high-quality freshwater pearls that rival their saltwater counterparts. Natural pearls, however, are rare and carry a premium due to the dangers and challenges associated with their harvest. Cultured pearls are often seen as more accessible alternatives, allowing for a wider array of options in the jewelry market. These pearls not only serve as beautiful adornments but also reflect the intricate relationship between human innovation and natural processes.
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Cultured pearl
A cultured pearl is a pearl that is created by a mussel or oyster farmer. The method can be used with either freshwater river mussels or saltwater pearl oysters. Cultured pearls are real pearls that are cultivated under controlled conditions, while natural pearls grow haphazardly in bivalves. Natural pearls are harvested by pearl divers who work in hazardous conditions to find the few gems available in the wild. Modern methods have resulted in cultured pearls that are as lustrous as many natural pearls.
![rssalemscience-20200812-3-185202.jpg](https://imageserver.ebscohost.com/img/embimages/ers/sp/embedded/rssalemscience-20200812-3-185202.jpg?ephost1=dGJyMNHX8kSepq84xNvgOLCmsE2epq5Srqa4SK6WxWXS "A cultured white pearl necklace. Flickr.com user "tanakawho" / CC BY (https://creativecommons.org/licenses/by/2.0)")
Overview
Pearls are gems that are produced in living creatures. They develop when an irritant finds its way into a mature bivalve, which means the mollusk is at least three years old. The irritant in nature is most likely a parasite. In a pearl farm, the irritant is called a seed or nuclei. It is inserted between the creature’s shell and mantle, the outer layer of its body. The irritant is usually a shell bead wrapped in a sliver of mantle. The inner surface of the oyster’s shell indicates the color of the pearl it will produce. This helps farmers choose the oysters whose mantles will be slivered to produce the seeds. The live mantle tissue grows onto itself and encloses the bead in a pearl sac. Both natural and cultured pearls owe their luster to a fluid called nacre. The bivalve’s immune system responds to the irritant by producing nacre, which coats the irritant. The bivalve continues to produce nacre, which deposits repeatedly on the irritant, slowly building up layer by layer.
Only one seed is implanted in each oyster. The implanted oysters are put into mesh panels tied to lines of rope in the ocean. Workers frequently scrub them clean to prevent organisms from growing on them.
A quality pearl takes time to develop. A thick coating of nacre takes at least three years to form, although some farmers harvest lower-quality pearls in less time. The lustrous nature of a pearl comes from a thick coating of nacre, but sometimes even cultivated pearls are dull, misshapen, or pocked.
In the past, freshwater pearls were rice-grain sized and often irregular in shape. They were of lower quality than saltwater pearls. More sophisticated farming techniques have resulted in very high-quality freshwater pearls, however.
Natural pearls are increasingly rare, and therefore more valuable. Only one in every ten thousand wild pearl oysters produces a pearl of value. They are difficult to find and divers collected pearl oysters face many dangers, including predators and drowning. Few oysters contain pearls, and pollution has affected the population of pearl oysters in many areas.
Cultured pearls of varied shapes, sizes, and colors can be produced by using different varieties of oysters. For example, Akoya pearls, which are farmed off the coast of Japan, grow to about 12 millimeters and are often artificially colored. South Sea pearls, which are regarded as the most valuable cultivated pearls, can grow to 20 millimeters and are naturally gold and silver.
Nacre, also known as mother of pearl, is not just beautiful but also extremely durable. Researchers have discovered that it is composed of molecules of calcium carbonate arranged into nano-layered sheets. At high magnification, it resembles a brick wall of thin interlocking layers.
Bibliography
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