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The world renound ruby mines at Mogok, Burma

The sapphire mines at Bang Kacha, Chanthaburi, Thailand.

Gem mining at Pailin, Cambodia.

Sapphire mining at Bo Ploi, Kanchanaburi, Thailand

Ruby mining at Bo Rai, Trat, Thailand.

The marble village of Sagyin, Shan State, Burma.

Properties of Rubies & Sapphires

The word corundum originates from the Sanskrit word kurivinda. Corundum is a mineral to which both rubies and sapphires belong. The chemical composition of corundum is aluminium oxide (Al2 O3) with traces of various transition elements such as chromium (Cr). It is these transition elements that are responsible for producing the stone's colour. Chromium produces the finest red colour in rubies and also pink coloured sapphires. Chromium produces some of the finest colours found in many other gems like emeralds, jadeite, and chrome diopside to name a few. Other transition elements found in corundum include iron (Fe), vanadium (V) and titanium (Ti). Gem quality corundum comes in all colours with red corundum described as ruby and all other colours described as a sapphire with the name of the colour as a prefix. Corundum crystallizes in a hexagonal (trigonal) form with the six crystal faces meeting at 120 degrees.

Cut & polished rubies.

 

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Physical Properties of Corundum

 

Refractive Index

-

1.762 - 1.770

Birefringence

-

0.008 - 0.009

Crystal System

-

Hexagonal (trigonal)

Optic Character

-

Uniaxial (-)

Specific Gravity

-

3.97 - 4.03

Hardness

-

9

Pleochroism

-

Very Pronounced

Chemical Composition

-

Aluminium Oxide (Al2 O3)

Cleavage

-

None

Dispersion

-

0.008

 

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Ruby crystals in marble matrix from Jagdalek, Afghanistan.

 

Hexagonal bipyramid sapphire crystal.

 

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The cutting stages of a 13 carat pink sapphire

A thirteen carat rough pink sapphire crystal, viewed from four different angles.

The same stone pre-formed into a drop shape.

The finished stone weighing in at over eight carats.

 

 

 

 

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