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Ruby

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.

General

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]

Identification

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

nε=1.760–1.763

Birefringence

0.008

Pleochroism

Strong: purplish-red - orangy-red

Dispersion

0.018

Ultraviolet fluorescence

red under longwave