Ruby : red colored precious gemstone

Rubies are a variety of the mineral corundum (aluminum oxide). Their color ranges from pink to a deep blood red, the red being due to the presence of chromium. The word ruby derives from the Latin ‘ruber’ meaning red. Ruby and sapphire are both varieties of the mineral corundum and are two of the four precious stones. The other two precious stones are diamonds and emeralds. richblu obtains its fine rubies from Myanmar, Vietnam, Thailand and Mozambique.

The most precious rubies are those with the deepest red color. “Pigeon’s blood” or blood red rubies are the brightest and most valuable and will be much more sought after and expensive than others of similar quality, but less intense color.

In judging the value of rubies, after color, comes the clarity of the gems, as with diamonds. A clear stone is very highly prized, and priced, although if a ruby lacks rutile inclusions (needle-like crystals of rust-colored titanium oxide), it may be an indication that it has been heat-treated. Other important factors in determining the price of rubies are the cut and the carat (weight).

The ruby is the traditional birthstone for the month of July and the most expensive ruby on earth is the Sunrise Ruby, which sold for over $30 million in May 2015.

Category Mineral variety
Formula aluminium oxide with chromium, Al2O3:Cr
(repeating unit)
Crystal symmetry (Hexagonal scalenohedral, H-M symbol: (3 2/m), Space group R3c[1]
Color Near colorless through pink through all shades of red to a deep crimson
Crystal habit Terminated tabular hexagonal prisms.
Crystal system Trigonal
Cleavage No true cleavage
Fracture Conchoidal, splintery
Tenacity Brittle
Mohs scale hardness 9
Luster Subadamantine, vitreous, pearly (on partings)
Streak white
Diaphaneity transparent, translucent
Specific gravity 3.97 – 4.05
Optical properties Uniaxial –
Refractive index nω=1.768–1.772
Birefringence 0.008
Pleochroism Strong: purplish-red – orangy-red
Dispersion 0.018
Ultraviolet fluorescence red under longwave