Color	Bright red, brownish-red, purplish-red, dark red
Hardness	9
SG	3.9 - 4.1
RI	1.76 - 1.77
DR	.0008
Luster	Vitreous to adamantine
Mineral class	Corundum
Composition	Be3Al2SiO6

Ruby is distinguished and known by all for its fiery red color. Beside for its color, it is a most desirable gem due to its hardness, durability, luster, and rarity. Transparent rubies of large sizes are even rarer than diamonds. Transparent, flawless rubies exceed all other gems in value. (except for deeply colored "fancy diamonds"). Rubies must be transparent to possess gem value. Opaque or semi-opaque rubies have little value, even if they display asterism.

Ruby is a red variety of the mineral corundum. Sapphire, the other gem variety of corundum, encompasses all colors of corundum aside from red. In essence, ruby is a red sapphire, since ruby and sapphire are identical in all properties except for color. The color of ruby ranges from bright red to dark reddish-brown. The most preferred color is a deep blood red with a slightly bluish hue. Such ruby is known as "Burmese Ruby" or "Pigeon's Blood Ruby". Ruby from Burma is famous for its exceptional coloring. However, Burmese ruby rarely exceeds several carats; large flawless Burmese rubies can be worth millions of dollars. Most rubies on the market are from Thailand, and these rubies have a brownish hue. They can be heat-treatmed to improve color. Heat-treating a ruby can also increase its transparency by removing tiny internal flaws.

Inclusions of tiny, slender, parallel Rutile needles in ruby cause a polished gem to exhibit asterism. Rubies displaying asterism are known as "Star Rubies", and if transparent are highly prized. Star rubies exists in six ray stars. Very rarely, twelve ray stars also occur. Occasionally, ruby also exhibits cat's eye effect.
Color zoning, which forms from growth layers that build up during the formation of the stone, is present in certain rubies.

Rubies were first synthesized in 1902. The process of creating synthetic rubies is known as the Verneuil process. Many rubies on the market are synthetic. Only experts can distinguish between natural and synthetic rubies.

Ruby is a tough and durable gem, but it is still subject to chipping and fracture if handled roughly.

USES
Ruby is faceted into many styles of cuts, although the brilliant and step cuts are the most preferred. Stones displaying asterism are polished as cabochons. Synthetic rubies are inexpensive and often used as a substitute for natural rubies.

Ruby is the birthstone for July.

VARIETIES
Burmese Ruby - Ruby with exceptional color (usually but not necessarily from Burma)
Pigeon's Blood Ruby - Blood-red ruby with a hint of blue
Star Ruby - Ruby displaying asterism
Cat's Eye Ruby - Ruby exhibiting cat's eye effect
Burma Ruby - Synonym of Burma ruby (above)
Verneuil Ruby - Synthetic, laboratory-grown ruby

FALSE NAMES
Many deceitful names are given to less valuable red gems in connotation with ruby. These names are used by unscrupulous dealers to confuse inexperienced buyers. Generally speaking, any time the word ruby is used with a prefix (except for those mentioned above), it is a fake. There is one gem in particular that requires special attention for this practice, for it so closely resembles ruby. This gem is pyrope garnet, for which the following names may be assigned:

Adelaide Ruby
American Ruby
Arizona Ruby
Australian Ruby
Bohemian Ruby
California Ruby
Cape Ruby
Colorado Ruby
Elie Ruby
Montana Ruby
Rocky Mountain Ruby


Beside for pyrope garnet, other reddish gems have also been assigned false names in connotation with ruby. These include:

Alabandine Ruby - almandine garnet
Ancona Ruby - rose quartz
Balas Ruby - pink to pale red spinel
Brazilian Ruby - pink topaz
Copper Ruby - cuprite
Garnet Ruby - garnet
Geneva Ruby - synthetic ruby
Ruby Spinel - red spinel
Siberian Ruby - red tourmaline
Spinel Ruby - red spinel

SIMILAR GEMSTONES
Ruby is identical in appearance to ruby spinel. In fact, many famous old "rubies" were determined to actually be spinel. The most famous ruby, the Black Prince's Ruby, set into the royal crown of England, was once thought to be the largest cut ruby. It was recently discovered to be spinel.

Garnet (particularly pyrope garnet) and tourmaline may also resemble ruby, but the great hardness of ruby can differentiate it from all other gems.

RECOMMENDED BOOKS

Ruby & Sapphire
By: Richard W. Hughes

Ruby and Sapphire Buying Guide
By: Renee Newman

Rubies and Sapphires (Fred Ward gem book series)
By: Fred Ward