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Ostriche con perle

Ostriche con perle

Gioielli Perle. Tipi di perle. Tagli di perle. Cura delle perle. Perle Video. Misurazione Perle. La nostra storia. Spedizione delle Perle. Polize di ritorno. Poliza per la privacy. They were born already bright and iridescent and they immediately express their everlasting beauty. Consequently, the mollusc, trying to protect itself, will secrete an organic substance, named nacre. The nacre will accumulate on the foreign body for millions of layers, giving rise to the pearl. Nacre is a calming substance, composed by microscopic calcium carbonate crystals, perfectly aligned with each other. Cultured pearls, on the contrary, are the kind of pearls produced with a human intervention.

Indeed, a foreign body, named nucleus, is put into the tissue of the mollusc or oyster. After that, it begins the same natural process to the nacre secretion around the nucleus, resulting in the generation of pearl. Cultured pearls are the result of some discoveries made between the end of the 19th century and the beginning of the 20th century, by a few Japanese researchers. Kokichi Mikimoto is the best known. He was among the first who discovered a specific technique to stimulate the creation of a round pearl in the tissue of an oyster. After the human intervention — that consist of, as previously said, the addition of a nucleus in the oyster so that it starts to secrete some nacre around it — oysters are constantly checked for many years.

Thanks to this meticulous and long process, thousands of pearl oysters can develop, and costs are reduced. The nucleus of a cultured pearl is a little sphere of nacre. It is installed in the gonad — the sexual organ of a sea mollusk — or in the pearl sack of the mollusc cover. As a reaction of the intrusion, the mollusc secretes nacre around the nucleus in order to expel it. There are many nucleation techniques, but all of them have the same principle: During the nucleation process, oysters are opened more or less two or three times and an incision is done on the gonad. Then, specialists introduce the nucleus in the split and, after that, put a little layer of oysters cover in the oyster in order to totally surround the nucleus and to close the gonad again.

For a good oyster reaction, the insertion of the nucleus has to be done with a surgical precision. The quality of the pearl depends on the quality of the piece of cover introduced. Akoya oysters die after the collection of the pearls. On the contrary, the oysters which produce Tahitian and Australian pearls survive at the pearl extraction and can be nucleated again. Moreover, since they have developed during the first nucleation, from the second one they can produce bigger pearls. Anyway, after some nucleations, specialists prefer to leave the oysters calm so that they can reproduce and facilitate the restocking of the farming.

Generally, the pearl production process with freshwater cultivated molluscs is activated using only a piece of tissue of a donor mollusc, without any nucleus inside it. Differently from Akoya oysters, with freshwater oysters is not the gonad to be cut, but the oysters cover. Both valve sides can be cut and, on average, freshwater molluscs produce between 24 and 32 pearls during each cultivation cycle. After the nucleation and the chirurgical human intervention, oysters need some weeks to recover.

During this period, many oysters reject and expel the nucleus inserted and others get sick. Then, implanted oysters, put in cages or nets, are placed in their habitat. Here, they will produce amazing pearls. According to the kind of oyster, the production of high quality pearls can last from a few months to many years. During this period and for all the growing process of the molluscs, farmers are very careful and check them many times. Moreover, they constantly verify the quality and the temperature of the water and its environment. Some oyster categories require more attention than others, since some oysters, for instance, are more delicate and sensitive to water temperature.

Farmers regularly raise and lower the nets in order to maintain the water temperature unvaried. Basically, it is a constant watching in order to guarantee the success of the culture. Each year, indeed, only a few of the nucleated oysters will generate high quality pearls. Many of them do not survive after the nucleation process, and many others are too much weak and easily at risk of diseases. Sometimes, after heavy rain, the water salinity changes, and this put into suffering the oysters. This way, a perfect pearl is really uncommon. Akoya pearls are generated by Pinctada Fucata Martensii, which is better known as Akoya oyster.

This mollusk is mostly cultured in Japan, China and Vietnam. Renowned for their excellent brightness, Akoya pearls are considered as the most classical pearls. Akoya oyster is the smallest pearl oyster and it produces pearls from 2 to 10 mm. Generally, they are perfectly round and perfect to create bright and charming jewels. During the last years, the Chinese have surpassed the Japanese in the production of little and medium-quality Akoya pearls. Then, because of Chinese pressure, many Japanese farmers have focus on the cultivation of high quality Akoya pearls with a bigger diameter. Australian pearls are the bigger ones cultivated all over the world. Their average size is of 13 mm, with diameters from 9 to 20 mm.

This is a reason why Australian pearls are extremely rare. They are produced by the Pinctada Maxima oyster and they are cultivated between Indian and Pacific Oceans, mainly in Australia, but also in the Philippines and Indonesia. Only a little percentage of Australian pearls is perfectly round. It is a very complex and long process, then, to realize a necklace composed of perfectly round and uniform Australian pearls. This process, indeed, can require many months. There are two types of Pinctada Maxima: The difference between them is the colour of the external edge of the internal part of the shell.

This will determinate the colour of the pearls. In these oysters it can be introduced only a nucleus at a time. There are many factors which help to reach such diameters.

I gioielli dei mari: le perle

Una perla è una struttura sferica costituita da carbonato di calcio in forma cristallina (aragonite) deposto in strati concentrici, prodotta dai tessuti viventi – in particolare dal mantello – dei molluschi (tipicamente le ostriche). Il termine "perla " deriva dal latino "pernula", il nome con cui si indicava la Per creare perle con forme speciali, quando si estrae la perla. Le perle più pregiate sono prodotte da diverse specie di molluschi l'ostrica produce strati di madreperla, avvolgendo completamente e Oggi, grazie alla tecnologia, si riescono ad ottenere anche perle con colori particolari. Trovare una perla in un'ostrica di allevamento è un evento raro A inizio dicembre Antosh era seduto con un amico a un tavolo del Grand. del pezzetto di mantello è eseguita con estrema attenzione ed è determinante per il Le ostriche che producono invece le perle di Tahiti e le perle Australiane . Per creare perle con forme speciali, si immette un frammento di plastica sferico o con la forma scelta, che l'ostrica coprirà con la madreperla. Ostrica con perle multiple Una ventina di anni fa, presso Hurgada, in Egitto, sul mar Rosso, trovai un'ostrica perlifera (Pinctada margaritifera. Dimensione: 7 – 8 mm. Confezione:da 10 il-tempio.ashleyhower.com g. Forma: rotonda. Un' ostrica con una perla. Quantità: 10 il-tempio.ashleyhower.comaggio del prodotto.