The Pearls

COLOR: white-cream, white-silvery, white-pink, white-brown, yellow, yellow-orange, pink, green, blue, black.
CHEMICAL COMPOSITION: carbonate of calcium (CaCO3)82-92%, conchiolin (C32H48N2O11) 6-14%, water 2-4%.
HARDNESS: 3-4.
Density: 2,60-2,80.
Transparency: from opaque to translucent.
INDEX OF REFRACTION: 1,520-1,660.
FLUORESCENCE: weak (UV 366 mm).

The pearls are produced from oysters. One pearl shape when a stranger body, like a particle of sand, firm in the palleale cavity. It comes covered from layers succeeded of nacre, in order to defend the woven ones of the animal from the irritation. They are deposited you vary soccer layers that in combination with other minerals, create these particular valuables. The pearls we remember that it is formed practically from nacre better known like nacre. In order to create pearls with special shapes, when the pearl from the oyster is extracted, they put a plastic fragment with the shape chosen, than the oyster it will cover with nacre. The result is that, after wait years, the pearl that is born it has the magnified shape of the fragment begins them. The common color in pearls is the white, but pearls can be also found in rose, cream, viola dark, grey and black. Thanks to the technology and years of study, today we can also have pearls with strange color like green, blue, orange that come above all used in the costume jewellery. When it is spoken about black pearls, beyond to the Akoya and to those of river, it is believed endured next to the most expensive pearls of Tahiti which are much valuable and particularly beautiful. The value of pearls but, is not not only distinguished from the color, but also from the shape and the lustro, that is the light that succeeds to reflect. A curiosity to know is that, with the exception of the others, the oysters that create black pearls are much more delicate and in every cultivation they die some tantissime. This is an other factor that them renders rare therefore expensive and. There are two pearl categories: the sweet water pearls and the salata water pearls. As it says the same word, the sweet water pearls come cultivated in lagos and the rivers, while the others often come from the ocean and a lot from lagoons. The three salt water pearl categories are the Akoya, the Tahiti pearls and the most expensive and rare pearls of South Sea.


MAINTENANCE
The pearls can have also a persistence of hundred of years, if, in their maintenance, it is respected fundamental rules. In the composition of these gems, it is a determined water amount that, in case of excessive dehydration, provokes changes of structure, with irreversible damages that one can put in danger the pearl beauty. In order to avoid these difficulties, the pearls cannot be put posterior in dry places or places of humidity and after them to have porsi, before putting them of new in their guard they need being cleaned up, because, the cosmetic can deteriotate pearls.