Types of Cultured Pearls
Keshi pearls, although they often occur by chance, are not considered natural pearls. They are a byproduct of the culturing process, and hence do not happen without human intervention. These pearls are quite small: typically a few millimeters in size. Keshi pearls are produced by many different types of marine mollusks and freshwater mussels in China. Keshi pearls are actually a mistake in the cultured pearl seeding process. In seeding the cultured pearl, a piece of mantle muscle from a sacrificed oyster is placed with a bead of mother of pearl within the oyster. If the piece of mantle should slip off the bead, a pearl forms of baroque shape about the mantle piece which is entirely nacre. Therefore, a Keshi pearl could be considered superior to cultured pearls with a mother of pearl bead center. In the cultured pearl industry, the resources used to create a mistaken all nacre baroque pearl is a drain on the production of round cultured pearls. Therefore, they are trying to improve culturing technique so that keshi pearls do not occur. All nacre pearls may one day be limited to natural found pearls. Today many "keshi" pearls are actually intentional, with post-harvest shells returned to the water to regenerate a pearl in the existing pearl sac.
Tahitian pearls, frequently referred to as black pearls, are highly valued because of their rarity; the culturing process for them dictates a smaller volume output and they can never be mass produced because, in common with most sea pearls, the oyster can only be nucleated with one pearl at a time, while freshwater mussels are capable of multiple pearl implants. Before the days of cultured pearls, black pearls were rare and highly valued for the simple reason that white pearl oysters rarely produced naturally black pearls, and black pearl oysters rarely produced any natural pearls at all.
Since the development of pearl culture technology, the black pearl oyster found in Tahiti and many other Pacific Island areas has been extensively used for producing cultured pearls. The rarity of the black cultured pearl is now a "comparative" issue. The black cultured pearl is rare when compared to Chinese freshwater cultured pearls, and Japanese and Chinese akoya cultured pearls, and is more valuable than these pearls. However, it is more abundant than the South Sea pearl, which is more valuable than the black cultured pearl. This is simply because the black pearl oyster Pinctada margaritifera is far more abundant than the elusive, rare, and larger south sea pearl oyster Pinctada maxima, which cannot be found in lagoons, but which must be dove for in a rare number of deep ocean habitats or grown in hatcheries.
Black pearls are very rarely black: they are usually shades of green, purple, aubergine, blue, grey, silver or peacock (a mix of several shades, like a peacock's feather).
Black cultured pearls from the black pearl oyster – Pinctada margaritifera – are not South Sea pearls, although they are often mistakenly described as black South Sea pearls. In the absence of an official definition for the pearl from the black oyster, these pearls are usually referred to as "black pearls".
The correct definition of a South Sea pearl – as described by CIBJO and GIA – is a pearl produced by the Pinctada maxima pearl oyster. South Sea pearls are the color of their host Pinctada maxima oyster – and can be white, silver, pink, gold, cream, and any combination of these basic colors, including overtones of the various colors of the rainbow displayed in the pearl nacre of the oyster shell itself.
South Sea pearls are produced in various parts of the world. White ones tend to come from the Broome area of Australia while golden ones are from the Philippines. Pearls are also produced in the Cook Islands and one farm in the Sea of Cortez, Mexico, from Concha Nácar the rainbow lipped oyster; these pearls fluoresce red under ultraviolet light.
Other articles related to "cultured, pearls, cultured pearls":
... Commercially available cultured buttermilk is milk that has been pasteurized and homogenized (if 1% or 2% fat), and then inoculated with a culture of lactic acid bacteria to simulate the naturally occurring ... Some dairies add colored flecks of butter to cultured buttermilk to simulate residual flecks of butter that can be left over from the churning process of traditional buttermilk ... In the early 1900s, cultured buttermilk was labeled artificial buttermilk, to differentiate it from traditional buttermilk, which was known as natural or ordinary buttermilk ...
... A cultured neuronal network is a cell culture of neurons that is used as a model to study the central nervous system, especially the brain ... Often, cultured neuronal networks are connected to an input/output device such as a multi-electrode array (MEA), thus allowing two-way communication between the researcher and the network ... Cultured neurons are often connected via computer to a real or simulated robotic component, creating a hybrot or animat, respectively ...
... Cultured marble, cultured granite, and cultured onyx describe solid surfaces colored to resemble natural stone ...
... Cultured freshwater pearls are pearls that are farmed and created using freshwater mussels ... These pearls are produced in Japan and the United States on a limited scale, but are now almost exclusively produced in China ... Federal Trade Commission requires that farmed freshwater pearls be referred to as "freshwater cultured pearls" in commerce ...
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