Sapphire is one of the top four in popularity of gems; Diamond, Sapphire, Ruby, and Emerald. This is mostly due to its beauty, variety of colors and toughness as a jewelry gem. It is typically thought of as being a blue gem, but it is available in many other colors including blue-green, green, violet, purple, orange, yellow, golden, peachy pink, pink, colorless, and black. Ruby is the red or the pinkish red variety of Corundum. With a Moh’s hardness of 9.0 and no cleavage, it is a very durable gem for jewelry.

Sapphire is available from many locations around the world. Some of these locations, like Cambodia, Ceylon, and Kashmir, are well known for their fine Sapphires.

Category:  Oxide mineral
Formula: Al2O3
Aluminium oxide
Crystallography: Trigonal – Hexagonal Scalenohedral
Crystal Habit: Crystals hexagonal, prismatic or steeply dipyramidal, tabular, rhombohedral, rarely acicular, typically rough, to 1 m; sectorially striated on [0001] k [1011]. Also granular, massive.
Twinning: Common lamellar k [1011], may be an exsolution phenomenon. Contact or penetration twins on [0001] or [1011], rare.


Cleavage: None; Partings on [0001] and [1011]
Fracture: Irregular/Uneven, Conchoidal
Tenacity: Brittle
Hardness (Mohs): 9.0
Density: 3.99 – 4.10 (g/cm3)
Luminescence: None
Radioactivity: Not Radioactive


Color: Colorless, Gray, Brown, Pink, Orange, Yellow, Green, Blue to Cornflower Blue, Violet; may be color zoned, asteriated
Transparency: Transparent to Translucent, Opaque
Luster: Adamantine to Vitreous, Pearly on partings
Refractive Index: 1.760 – 1.772  Uniaxial ( – ); commonly anomalously Biaxial
Birefringence: 0.008 – 0.009
Dispersion: 0.018  (low)
Pleochroism: Weak; e = blue-green to yellow-green, o = pale to deep blue
Other: Asterism often present due to oriented needle-like inclusions or to colloidal or other material deposited in oriented tubules.