Sapphire
Sapphire is the gem-grade variety of corundum (aluminum oxide, Al2O3) in any color other than red. Blue is the iconic hue, but pink, yellow, green, and color-change variants are all valued.
基本資料
| 化學式 | Al2O3 |
|---|---|
| IMA 代號 | Crn |
| 施特龍茨分類 | 4.CB |
| 晶系 | 三方晶系 |
| 點群 | -3m |
| 變種來源 | Corundum |
| 模式產地 | (gem variety of corundum), Sri Lanka |
Sapphire is the gem variety of corundum (aluminium oxide) in every colour except red — red corundum is called ruby. The classic blue is caused by traces of iron and titanium together; sapphire also occurs in yellow, pink, green, purple and the rare pinkish-orange 'padparadscha'.
Properties
Corundum is trigonal and very hard (9), second only to diamond, giving sapphire excellent durability for jewellery. Rutile 'silk' inclusions can yield star sapphires and also help distinguish natural from synthetic stones.
Occurrence
Kashmir, Myanmar and Sri Lanka produced the legendary historic blues; today Madagascar, Australia, Thailand and East Africa are leading sources. Heat treatment to improve colour and clarity is routine and should be disclosed.