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Ruby CrystalRuby Crystal
Ruby is a red corundum mineral with a chemical formula A2O3 aluminum oxide with chromium. It is the chromium that give rubies their red color. It is a very hard mineral, a 9 on the mohs scale. Only diamonds are harder at a 10. The word ruby comes from ruber, Latin for red. Other varieties of corundum are called sapphires.

Rubies are usually found in flat hexagonal crystals.


The value of rubies is based on their clarity and color. The most desirable color is a deep blood red. They can range in color from lighter pinks to red sometimes having a less desirable brownish hue. Large clear rubies can be worth millions!

Rubies are the most valuable and popular red gemstone. They are used in all types of jewelry and traditionally has been used to decorate highly valued objects like crowns, thrones, and scabbards.


Rubies are the birthstone for July.


Gem quality rubies or sapphires form in metamorphic rock like shist or gniess or igneous rock like basalt. It is possible to mine these hard rock sources but it is difficult and expensive. Luckily because these gems are so hard they weather out of relatively softer host rock. They end up in the gravel beds of streams. The high Density of the corundums cause them to be deposited in pockets. The gravel from these pockets can be sifted by hand. This is the way most rubies are mined.

In the modern era rubies can be heat treated to improve the color and clarity. This process has increased the value of otherwise low quality gems. 


Historically, the primary source of rubies has been Myamar (Burma). They have also been mined in Thailand,  well as in Afghanistan, , India,   in Madagascar, Nepal, Pakistan,In Sri Lanka, lighter shades of rubies (often "pink sapphires") are more commonly found.

Mineral Properties of Ruby

Chemical formula: A2O3 aluminum oxide with chromium

Color(s): light pink to deep red
Streak: White
Luster: vitreous to adamantine
Transparency: transparent to opaque
Crystal system: trigonal
Crystal Habits: tabular hexagonal crystals.
Specific Gravity: 4.0 to 4.1
Hardness (Mohs): 9
Cleavage: none
Fracture: conchoidal to uneven
Uses: Mineral Specimens, jewelry and ornamentals
Associated Minerals: Saphire, topaz,spinel Location: Includes Myamar (Burma), Thailand, Afghanistan, India, Madagascar, Nepal, Pakistan, and Sri Lanka,

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