Jumat, 04 November 2011

Sapphire

Sapphire or its mineralogical name CORUNDUM is a well known gemstone. It's an aluminum oxide with traces of coloring elements. Sapphires can be of all possible colors, including pink, and can also be colorless; partly colored sapphires are quite common. There are also natural sapphires which change color: they are purple in daylight and red in electric light.

Sapphires are very hard and can be worn in any form of jewelry and have long been popular as ring stones. Because of their high density they are usually smaller than most other gemstones of the same weight. They vary in transparency from complete clarity, through various degrees of cloudiness to sub-translucency, but some slight inclusions are not necessarily regarded as defect. The shimmering whitish sheen produced by microscopic needles of rutile and known as 'silk' is accepted as an attractive attribute within reason and as a proof that a stone is genuine.

As usual with gemstones, there is a vast difference in value between really fine specimens and those of lesser quality. Among sapphires, those with rich , but not too deep, blue color are prized most highly. The other colors are less in demand, perhaps because it is not generally realized that sapphires exist in all possible colors (except red). Padparadschas (orange sapphire) of rich color, a reddish-orange, are rare and fetch high prices among collectors.

In jewelry setting sapphires and rubies are often combined with diamonds which set off their color to perfection. Larger stones are often surrounded with small diamonds, smaller stones may be set alternately with diamonds of a matching size as in the traditional three stone or five stone rings. In such cases it is important that the stones should match exactly in color and that they should conform to the design in size. If one stone is lost, it may be quite difficult to match it.

Every conceivable method of imitation and synthesis has been employed to produce artificial rubies and blue sapphires. Glass and synthetic spinel have been used, as well as hydrothermal substitutes. Synthetic sapphires can now be produced in almost any shape and is widely used in the jewelry industry. Colorless synthetic sapphire has long been used as a diamond substitute on account of its hardness and purity.

Source : http://magazine.gem-fashion.com/sapphire.html

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