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 Sapphire |
| Crystal structure : Rhombohedral |
Composition : Aluminum oxide |
| Specific gravity : 4.00 |
Hardness : 9 |
| Refractive index : 1.76-1.77 |
Birefringence : 0.008 |
| Variety : Corundum |
Pleochroïsm : according to color |
Cut :     |
Sapphires can have several colors:
- blue: calls sapphire
- green: calls green sapphire
- yellow: calls yellow sapphire
- pink: calls pink sapphire
- violet: calls purple sapphire
- orange: calls orange sapphire also said “Padparadsha”
- colourless: calls leuco sapphire
In brief, the red corundum is called ruby, the other corundums are sapphires, knowing that the word sapphire without adjective indicates blue corundum.
The colouring of sapphires is due to titanium and iron. The color violet is due to vanadium, the colors yellow and green with a less content of iron, with chromium for the pink.
The most seeked color is pure blue cornflower.
Sapphire is a stone having inclusions (liquid, crystals,…). Rutile inclusions allow the sapphires cut out of cabochon to have the effects of asterism (star sapphire or cats eye). |
| Sapphire takes from Greek “sappheiros” meaning “beautiful thing/blue”. Before the XIXth century, where one identified the ruby and various sapphires like belonging to the veraity of corundums, green sapphire was called “Eastern Peridot”, yellow sapphire “Eastern Topaz”. In antiquity, the lapis lazuli was also called sapphire. |
The most famous sapphires are:
- Star sapphire “Star of India” in American Museum of New York (536 cts)
- Black star sapphire “Star of Midnight” in American Museum of New York (116 cts)
- Star sapphire “Star of Asia” in Smithsonian Institute of New York (330 cts)
- Sapphires “St Edward” and “Stuart”, royal jewels of England
- Sapphires representing the heads of Washington, Lincoln and Eisenhower (2000 cts each one)
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| Deposits : |
| The countries having deposits are : |
Country |
Quantity |
Quality |
Comment |
| Burma |
Important |
Good rare quality |
+ large star sapphire of the world: 63.000 cts |
| Australia |
Important |
Good rare quality |
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| Thailand |
Medium |
Good rare quality |
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| Sri Lanka |
Medium |
Good rare quality |
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France had a deposit in Cantal (sapphires of Expoilly): it is nothing any more but one geological curiosity.
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