About corund gemstones - rubys and sapphires -- Best Plastic Processing Machinery

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Date Posted: 13:07:55 10/26/14 Sun
Author: Knut Holt
Subject: About corund gemstones - rubys and sapphires

About Rubys, Sapphires and Related Gemstones

Rubies and sapphires belong to the mineral group corundum. Corundum is basically composed of aluminum and oxygen with the chemical formula Al2O3. Additive elements give the stones their characteristic colors. Corundum is very hard, with the degree 9 on the mohs scale, of which 10 is the hardest.

Crystals of corundum are fairly common in many volcanic rocks like syenite and metamorphic rocks like marble and gneiss. Single corundum crystals are common in the sand of beach and river shores. These originate from rock broken down. The crystals are typically six-sided blocks of variable size.

Pure crystals without faults are transparent and give a vivid luster. If a crystal consists of pure aluminum oxide it will also be colorless. These clear crystals are used as gemstones and are called white sapphires. Clear colorless corundum is also used in optical instruments.

Most corundum has however imperfect crystals and impurities that make them unclear or grey. These variants are used extensively in the industry as abrasives, for example is the sand in sand paper mostly made from corundum.

Transparent crystals of good quality with dissolved coloring elements are also used as gemstones, and some varieties obtain a high prize at the market.

Ruby is transparent corundum of red color due to presence of chromium in the crystal. A high valued ruby is usually strongly red like pigeon blood. Natural ruby crystals are seldom totally perfect, but generally contain inclusions of foreign minerals. The foreign elements are usually regarded as unwanted, and most natural rubys are heated or treated otherwise to make these elements less apparent. Important ruby deposits can be found in Tanzania, Madagascar, Vietnam, Nepal and Tajikistan.

Sapphire is the term for transparent corundum of other colors. Best known is the blue sapphire which gets that color from titanium dissolved in the crystal. Deep blue with some traces of purple is considered the finest color quality for blue sapphires. This variety gets the color form a combination of titanium and iron.

Sapphires can also be found in shades of yellow, green or pink. Sapphires of an orange-pink color, called padparadscha, is a very rare and beautiful variant and is sold for a high prize. The element vanadium will color a sapphire purple, iron will give a yellow or green color.

Sapphire can be found in Eastern Australia, Thailand, Sri Lanka, Madagascar, East Africa and various places in USA.

Since corundum has a simple composition, it can easily be manufactured synthetically by many methods. An early method still in use is the Verneuil process. It consists of treating aluminum powder with an oxygen-rich flame that is burning hydrogen. The produced corundum will drip off and is made to drop down into a boule and there form a single big crystal.

The crystals formed this way are of high quality and by adding other elements to the process, synthetic ruby and colored sapphire to be used as gemstones can be made. Most rubys and sapphires used today are synthetic.

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Knut Holt is an internet based consultant, author and marketer. Please go to this page to read about gemstones and jewelry and to find presentations of exciting products in this field.

http://www.panteraconsulting.com/salg3.htm

Please go here to find information and product presentations of a more extended area, for example: RC models and hobby, health and fitness, electronics, car equipment and fashion.

http://www.abicana.com

Article Source: http://EzineArticles.com/?expert=Knut_Holt

Article Source: http://EzineArticles.com/6680766
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