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The Best and Most Comprehensive Guide to Sapphires in Los Angeles and on the Web!
Copyright © 2006 INTA GEMS, Inc. All rights reserved.
The Sapphire Crystal
Sapphires belong to the mineralogical family known as corundum, made up primarily of aluminum oxides (Al2O3). Corundum minerals are known to have hexagonal crystal structures with very high durability and hardness.The only crystal harder than corundum is the diamond.
Sapphires are rated 9 on the Mohs hardness scale of 1 to 10. The Mohs scale was developed by Friedrich Mohs in 1812 and has been a valuable aid in identifying minerals ever since. Here are the ten levels of hardness in minerals on the scale:
10 Diamond
9 Corundum (Sapphires)
8 Topaz
7 Quartz (Amethyst, Citrine)
6 Feldspar
5 Apatite
4 Fluorite
3 Calcite
2 Gypsum
1 Talc (chalk)
Whenever two materials are brought into contact with each other, the harder material will always scratch the softer material. When two materials of the same hardness are brought together, they will scratch each other (at INTA Gems & Diamonds, we always recommend that you separate your gemstone jewelry pieces in storage so that they do accidentally scratch one another).
The Mohs scale is only a relative and greatly simplified scale. But it does suffice for basic hardness comparisons. Sapphires are incredibly hard and durable crystals, which makes them especially suitable for jewelry pieces most susceptible to wear and tear such as rings.