Corundum
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Physical & Optical Properties
Category
Semi-Precious Gems
Mohs Hardness
9.0
Specific Gravity
3.9 – 4.05
Refractive Index
1.758 – 1.78
Crystal System
Trigonal
Luster
Adamantine,Vitreous
Cleavage
None
Fracture
Uneven,Conchoidal
Color
various
Birefringence
0.007
Dispersion
0.018
Pleochroism
Dichroism: blue - violet-blue and greenish-blue; green - yellowish-green; yellow - pale yellow; purple - violet; orange, yellowish-red - deep crimson.
Mohs Hardness
| Mohs | Reference mineral | Corundum |
|---|---|---|
| 1 | Talc | |
| 2 | Gypsum | |
| 3 | Calcite | |
| 4 | Fluorite | |
| 5 | Apatite | |
| 6 | Orthoclase | |
| 7 | Quartz | |
| 8 | Topaz | |
| 9 | Corundum | ● |
| 10 | Diamond |
Crystal System
Value & Market
Price Tier
Fine ($500-5,000/ct)
Where to Buy Corundum
Blue Nile
Fine jewelry retailer
James Allen
Gemstone jewelry
Brilliant Earth
Ethically sourced gems
Amazon
Wide selection
Links may earn a commission at no extra cost to you.
About Corundum
刚玉是氧化铝矿物，以其极高的硬度（莫氏9，仅次于钻石）而著称，孕育了两种最珍贵的宝石：红色的红宝石和其他所有颜色的蓝宝石。无色刚玉（白宝石）纯净无瑕，各色蓝宝石则以斯里兰卡、缅甸、克什米尔和澳大利亚为主要产地，其中克什米尔矢车菊蓝蓝宝石被认为是世界上最完美的蓝色宝石。
On this page
Jewelry Use
Durability
10/10
Suitable for daily wear
Science FYI Family
Frequently Asked Questions
What is Corundum?
刚玉是氧化铝矿物，以其极高的硬度（莫氏9，仅次于钻石）而著称，孕育了两种最珍贵的宝石：红色的红宝石和其他所有颜色的蓝宝石。无色刚玉（白宝石）纯净无瑕，各色蓝宝石则以斯里兰卡、缅甸、克什米尔和澳大利亚为主要产地，其中克什米尔矢车菊蓝蓝宝石被认为是世界上最完美的蓝色宝石。
What is the hardness of Corundum?
Corundum has a Mohs hardness of 9.0, making it excellent for use in jewelry.
What color is Corundum?
Corundum is primarily Various.
How much does Corundum cost?
Corundum falls into the Fine ($500-5,000/ct) price range. Prices vary based on color, clarity, cut, and origin.
What is the crystal system of Corundum?
Corundum belongs to the Trigonal crystal system.