Chemical formula: Al2O3:Cr
The ruby is a variety of the mineral corundum. The red of the mineral comes from the presence of chromium.
Mohs scale: 9.0
Color: Near colorless through pink through all shades of red to a deep crimson
Crystal system: Trigonal
Crystal habit: Terminated tabular hexagonal prisms
Cleavage: No true cleavage
Fracture: Conchoidal, splintery
Luster: Subadamantine, vitreous, pearly on partings
Specific gravity: 3.97- 4.05
Ultraviolet fluorescence: red under longwave UV light
Ruby is one of the four precious gemstones. Ruby, diamond, emerald and sapphires being classified as the four precious gemstones.
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.
Some rubies show a three-point or six-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. Furthermore, rubies can show color changes—though this occurs very rarely—as well as chatoyancy or the “cat’s eye” effect.
The Mogok Valley in Upper Myanmar(Burma) was for centuries the world’s main source for rubies. This area is known for the rubies that are described as blood red or pigeon’s blood. They are considered to be some of the best colored rubies in the world.
Rubies have been found in Thailand, Cambodia, Burma, India, Afghanistan, Australia, Nambia, Columbia, Japan, Scotland, Brazil and Pakistan. In the US, rubies have been found in Montana, North Carolina, South Carolina, Georgia and Wyoming.
The first laser was made of a man made red ruby crystal.
The Hope Ruby:
Sold for $6.7 million dollars in 2012
The Sunrise Ruby: The world’s most expensive ruby. 25.6 carat pigeon blood ruby from Burma. It sold for $30 million dollars in 2015 by Sotheby’s auction in Geneva, Switzerland.
Sold for $30 millions dollars in 2015
Rosser Reeves Star Ruby: 138.7 Carat ruby from Sri Lanka. Was donated to the Smithsonian museum. In 1966, it was insured for $150,000.00.
DeLong Star Ruby: A 100.32 carat oval cabochon star ruby which was discovered in Burma in the 1930’s. It was sold to Edith Haggin DeLong for $21,400.00 and she donated it to the American Museum of Natural History in 1937.
The Liberty Bell Ruby: the largest mined ruby in the world, found in east Africa in the 1950s. It weighs four pounds, is eight and a half thousand carats, and is sculpted into a miniature form of the Liberty Bell.
$2 Million dollars
Stolen on November 1, 2011 and has never been recovered.
$10,000 reward offered for its return but police have little hope the Liberty Bell Ruby will be returned.
Neelanjali Ruby: At 1370 carats, it is the world’s largest double-star ruby.
world largest double star ruby.
Prince of Burma: An uncut ruby crystal on a marble deposit. Weighing approximately 950 carats, it is mostly gem quality. It was found in the Dattaw Mine in Mogok, Myanmar in 1996.