 Ruby , the king of gemstones is considered one of the most valuable gemstones on Earth. The fiery red color of ruby is thought to be from an inextinguishable flame from within. The name 'ruby' derives from the Latin word 'rubens', which means 'red'. Ruby gemstones have everything a precious stone should have: color, hardness and brilliance.
Ruby is the red variety of the mineral cornudum, one of the hardest minerals on Earth. The term 'corundum', is derived form the Sanskrit word 'kuruvinda'. Pure corundumus actually colorless. Slight traces of elements such as chrome, iron or titanium are what give these gemstones their color. Chrome is the element that gives ruby its wonderful color.
Only red corundum can be called ruby, all other colors are Sapphire. All corundum gemstones have excellent hardness, On the Mohs Scale their score of 9 is second only to that of the diamond.
Some rubies display a wonderful silky shine, the so-called 'silk' of ruby. Very fine needles of rutile that grow within the stone while it is forming cause this phenomenom. Inclusions do not impair the quality of the a ruby unless they decrease the transparency of the stone. In fact, these inclusions are considered the ruby's 'fingerprint', a statement of its individulaity and proof of its genuineness and natural origin.
For over two thousand years rubies have been heat treated to enhance their reddish-pink color and to remove the bluish hues. Heat treatment was accomplished by using simple tools, such as a blow-pipe and charcoal burner. Today heat treatment is done using a combination of chemicals such as beryllium, borax, lead and tantalum. Heat-treatment temperatures range for 1500 to 1800 degrees Celcius for a period of two to ten hours.
Rubies have historically been mined in Thailand, Cambodia and Afganistan but cn be found in mines around the world. A ruby's color and qualities of light are often dependent on where the stone was mined. Some common varieties of ruby include; Burmese Ruby - ruby with exceptional color, Pigeon's Blood Ruby - blood-red ruby iwth a hint of blue and Star Ruby - a ruby displaying *asterism.
*Asterism - Effect exhibited on some minerals causing it to reflect a billowy, star-like formation of concentrated light which moves around when the mineral is rotated. Asterism is caused by dense inclusions of tiny, parrallel, slender fibers in the mineral. Minerals that display asterism may exhibit four, six and sometimes even twelve rayed 'stars'.
Sources:
Simon & Schuster's Guide to Gems and Precious Stones c1986 Edited by Kennie Lyman
Gems: A lively Guide for the Casual Collector by Daniel J. Dennis, Jr c1999 Harry N. Abrams
http://www.gemstone.org/gem-by-gem/english/ruby.html |
