Precious and coveted ornaments, now the subject of a prosperous and profitable industries, pearls are, however, above all, creations of nature.
Gallery (15) Precious and coveted ornaments, now the subject of a prosperous and profitable industries, pearls are, however, above all, creations of nature. Nothing could have been there - no ornaments, no metaphors involving pearl, or millions of dollars - if he had not first existed natural process: some species of molluscs have acquired, during evolution, learning to isolate a body stranger entered the body, surrounding it with layers of nacre and thus making it harmless. Prosaic? No. Fascinating. The result of this normal physiological process, defense, is magnificent structure called gem. Genesis of a pearl begins with a trivial fact - and unpleasant. One day, a piece foreign organic matter, or a parasite reaches the body shellfish, or accidental injury makes a piece of mantle tissue to reach another part of the body. Bothered by the intruder, which can not easily escape (he can not pull out like us, with his hand, entered a pebble in the shoe), clams learned, with time (hundreds of millions of years) own method of mitigating disturbing sensation: foreign body cover with a layer-layer flat material, limestone, thus isolating it and making it harmless, transforming it into an inert formation, rounded, less irritating to soft tissues and, if not can be eliminated, at least it is easier to bear. 
Most molluscs have this defense mechanism, so it can produce most of the limestone formations of different shapes, pearls can be considered a very broad sense of the term. But most do not have commercial value - calcareous concretions are small without too attractive appearance without gloss, and of interest only to collectors or scientists as some curiosities of nature.what jewelers call "pearls" - parties pearl gloss, silky - are produced by a small number of bivalve molluscs ("shell", as called popular) that secrete a particularity of a special material which forms the interior shell: nacre. The same material is used to isolate the shell and foreign body irritant, appearing as pearl. Pearls true, false pearls
A natural pearl is formed of concentric layers of aragonite, a form of calcium carbonate crystallized in the form of hexagonal plates with thickness of 0.5 microns, strengthened by thin layers of a protein called conchiolină. Pearls formed naturally from accidental penetration of a foreign body in the cloak shell, are rarely found, hence the exorbitant prices that are traded. In the twentieth century when the foundations were industrial production type, the market was flooded pearls cultured pearls, much cheaper than the "wild". Pearl culture is based on a combination of human intervention and natural processes of deposition of the layers of nacre around a foreign body, consisting of introducing human intervention in the soft tissues of the shell (mantle) that the foreign body.
Cultured pearls, even when produced in large quantities are not yet readily available. Shell needs to produce a pearl years - with so many years, how much bigger the pearl. Only about 5% of cultured pearls are high quality, with almost perfect sphericity and iridescent luster that make them suitable to be used in luxury jewelry.
natural pearls can be distinguished from the culture by X-ray examination on market moving large quantities of imitation pearls, made by processes, not bred oysters. Some are made of natural materials (such as pieces of pearl shells and polished coming from the form of spherical beads), others, such as so-called Mallorca pearls are glass spheres coated with several layers of essence of the Orient - a mixture containing, inter alia, that give the appearance of fish scales shimmer in an attempt to mimic the appearance of real pearls. "farms" of pearls
Cultured pearls, even when produced in large quantities are not yet readily available. Shell needs to produce a pearl years - with so many years, how much bigger the pearl. Only about 5% of cultured pearls are high quality, with almost perfect sphericity and iridescent luster that make them suitable to be used in luxury jewelry.natural pearls can be distinguished from the culture by X-ray examination on market moving large quantities of imitation pearls, made by processes, not bred oysters. Some are made of natural materials (such as pieces of pearl shells and polished coming from the form of spherical beads), others, such as so-called Mallorca pearls are glass spheres coated with several layers of essence of the Orient - a mixture containing, inter alia, that give the appearance of fish scales shimmer in an attempt to mimic the appearance of real pearls. "farms" of pearls
A small number of species of mussels produce pearls of commercial value and are therefore kept in pearl farms:
- Marine species of the genus Pinctada - approx. 6 species commonly exploited, living in the Mediterranean, Red Sea, Indian Ocean warm regions, the Pacific and Atlantic.
- Species of the genus Pteria also marine. A marine shell perliferă produce generally one pearl each time.
- Freshwater mussel species from the genera Hyriopsis (in Asia) and Amblema (North America) to these species, a single shell can produce more pearls once - even over 20.
Another species known historically for beautiful pearls they produce (and who has received scientific name) is Margaritifera margaritifera , also a freshwater clam, Europe and North America, unfortunately become threatened with extinction and today the subject of protection programs. Different species produce pearls of different shades - from white to yellow-gold ones (in Flipine), from pink to dark gray color the very expensive, commercially known as "black pearls of Tahiti." 
Today, cultured pearls are produced, largely by two processes: one that uses only fragments of tissue inserted into the shell, often resulting in irregularly shaped pearls, one in which, together with fragments of tissue, is inserted and a small round bead, around which will make shell nacre, resulting in a spherical bead closer - the most prized in jewelry.
Occasionally, beads folosec and otherwise, that they wear pearl shell, resulting Cultured pearls with unusual models. pearl farms are mainly in Asian countries for both freshwater pearls and for the "high".
Seeded oysters are grown in water, fixed nets. After 2-5 years after planting - depending on the species and type of pearls pursued - are removed and placed in the collection room. Here are "made" carefully extracting the pearls and shells that survive can then be sown again and put back in water for a new production cycle.
The method has a very good performance, unlike the primitive method used for centuries for harvesting natural pearls. Millions of shells were collected from large open brutally, with knives (and thus killed), in an attempt to find a pearl - which rarely happens. 
Today, cultured pearls are produced, largely by two processes: one that uses only fragments of tissue inserted into the shell, often resulting in irregularly shaped pearls, one in which, together with fragments of tissue, is inserted and a small round bead, around which will make shell nacre, resulting in a spherical bead closer - the most prized in jewelry.Occasionally, beads folosec and otherwise, that they wear pearl shell, resulting Cultured pearls with unusual models. pearl farms are mainly in Asian countries for both freshwater pearls and for the "high".
Seeded oysters are grown in water, fixed nets. After 2-5 years after planting - depending on the species and type of pearls pursued - are removed and placed in the collection room. Here are "made" carefully extracting the pearls and shells that survive can then be sown again and put back in water for a new production cycle.
The method has a very good performance, unlike the primitive method used for centuries for harvesting natural pearls. Millions of shells were collected from large open brutally, with knives (and thus killed), in an attempt to find a pearl - which rarely happens. 
Pearls of marine shells obtained farms, lagoons or bays increased, are more expensive than freshwater, from an objective reason: a sea shell can be seeded perliferă only one single piece of tissue (which triggers the formation perlier bag, where it will form the pearl) attached to a small polished spheres made of conch shell, will produce, therefore, a single pearl.
In contrast, freshwater mussels perlifere are more productive: a multiple sowing will the formation of several pearls in the same shell.
In contrast, freshwater mussels perlifere are more productive: a multiple sowing will the formation of several pearls in the same shell.
99% of pearls sold today are cultured pearls, the market is dominated by freshwater pearls produced in China. Not only do pearl oysters pearls Although best known, appreciated and shellfish products are marketed above, there are several species molluscs - snails this time - giving rise to less common pearls, rarely used, but have aesthetic value and commercial even for those who know how to appreciate. Pearls of these snails are generally pearly, but have a very special look - seem made of porcelain, with a fine sheen and delicate colors - pastel shades of yellow, pink or orange. Sea marine snail Melo melo (Indian Ocean - photo) and Strombus gigas (the Pacific) produce such pearl-rarities. And we live in a world record passionate, maybe you want to know which is the largest pearl found so far. It's one in the picture below: a huge white pearl (pearl without luster, but porcelain) "born" a huge shell (of the species Tridacna gigas ) and weighing 6.4 kg.
It is in the U.S., the private property of several people, descendants of those who bought from the heirs of her first American owner - some Wilburn Cobb, who brought in the Philippines in 1939 and died in 1979. Pearl - known as the "Pearl of Lao Tzu" - is "attached" and a captivating legend, that was raised in China and arrived at that size because, over the years 2500, was transferred successively more shells, becoming larger. He has no value for a jeweler - who would wear that? - But is still extremely valuable and is an impressive testimony to what nature can do in terms of shells and pearls.
Read more: http://www.bukisa.com/articles/577859_pearls-a-miracle-of-world-water#ixzz1bUbR4SEv
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