July – RUBY

The Ruby's rich red color speaks of love and passion. July's birthstone is among the most highly prized of gems throughout history. The Ruby was considered to have magical powers, and was worn by royalty as a talisman against evil. It was thought to grow darker when peril was imminent, and to return to its original color once the danger passed. The word Ruby comes from the Latin "ruber," meaning red. Large sized Rubies are very rare and valuable. The most beautiful crystals are thought to be from Burma, but quality Rubies are also found in India, Sri Lanka, Australia, Kenya, Tanzania, Afghanistan, Pakistan, and the United States. With its hardness and durability, it is a perfect engagement gem. And if worn on the left hand, ancient tradition has it that the Ruby will bring good fortune to its wearer.

Rubies are the red variety of the mineral corundum. Prices of rubies are primarily determined by color. The brightest and most valuable "red" called pigeon blood-red, commands a huge premium over other rubies of similar quality because of its color. A clear stone will command a premium, but a ruby without any needle-like rutile inclusions may indicate that the stone has been treated. All natural rubies have imperfections in them, including color impurities and inclusions of rutile needles known as "silk". Gemologists use these needle inclusions found in natural rubies to distinguish them from synthetics, simulants, or substitutes. Usually the rough stone is heated before cutting. Almost all rubies today are treated in some form, with heat treatment being the most common practice. However, rubies that are completely untreated but still of excellent quality command a large premium. Cut and carat (weight) also determine the price.

Some very rare rubies show a 3-point or 6-point asterism or "star". These rubies are cut into cabochons to display the effect properly. Asterisms are best visible with a single-light source, and move across the stone as the light moves or the stone is rotated. Such effects occur when light is reflected off the "silk" (the structurally oriented rutile needle inclusions) in a certain way. This is one example where inclusions increase the value of a gemstone. In other rare instances rubies can show color changes as well as chatoyancy or the "cat's eye" effect.

Appearance:

• Light to very dark green to very strongly bluish green
• Transparent to opaque
• Phenomena: chatoyancy, asterism (rare)

Variety and Trade names: Burma, Burmese, or Oriental ruby – red to slightly purplish red in medium dark tone and vivid saturation; generally considered finest color and was traditionally denoted by the term pigeon’s blood. Thai, Siam, or Siamese – dark red to brownish red or purplish red; African – typically orangey red

Misnomers:: none known

Typical Size Range:: melee sizes to 5 ct; faceted stones over 100 ct are known

Typical Cutting Styles: : faceted, cabochons

Cleaning Methods:

• Ultrasonic: Usually safe, but never for oiled stones
• Steamer: Usually safe, but never for oiled stones
• Warm soapy water: Generally safe, but avoid strong detergents and vigorous scrubbing for oiled stones

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References

Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6

GIA. (n.d.). GIA Grading and Reports. Retrieved July 29, 2011, from Gemological Institute of America:
http://gia4cs.gia.edu/cm/grading-reports.htm

ICGA. (n.d.). All About Gems. Retrieved July 30, 2011, from International Colored Gemstone Association:
http://www.gemstone.org/index.php?option=com_content&view=section&layout=blog&id=1&Itemid=69

IGS. (n.d.). IGS Reference Library. Retrieved July 29, 2011, from Internatonal Gem Society:
http://www.gemsociety.org/info/info.htm