Blue Sapphire

The blue sapphire is made of the mineral corundum (aluminum oxide). Its attractive blue color is due to traces of the elements iron and titanium. Commonly, the sapphires are heat-treated, called ‘thermal enhancement,’ in order to deepen the intensity of their color. Untreated sapphires are very rare and much more expensive than those which have been treated.

Blue sapphires are a natural phenomenon found all over the world, for example in Australia, Cambodia, Laos, Vietnam, Thailand, Sri Lanka, Madagascar, Cameroon, Tanzania and Nigeria.

Several shapes of heat-treated sapphires are manufactured by richblu : rounds, ovals, pears, marquises, octagons, etc. They are available in a variety of calibrated sizes. To find out the calibrated sizes we customarily stock, click here.

richblu can also offer precision-cut blue sapphires, that is,gems that are finely cut and crafted to elevate them to their maximum brilliancy. Our skilled craftsmen use specialist automated machines to produce the finest precision-cut gems. If you are interested in precision-cut sapphires, contact us for more information

Category Oxide mineral
Formula Aluminium oxide, Al2O3
(repeating unit)
Color Typically blue, but varies
Crystal habit As crystals, massive and granular
Crystal system Trigonal
Symbol (32/m)
Space Group: R3c
Fracture Conchoidal, splintery
Mohs scale hardness 9
Luster Vitreous
Specific gravity 3.95–4.03
Optical properties Abbe number 72.2
Refractive index nω=1.768–1.772
Birefringence 0.008
Pleochroism Strong
Melting point 2,030–2,050 °C
Fusibility Infusible
Solubility Infusible
Other characteristics Coefficient of thermal expansion (5.0–6.6)×10−6/K
relative permittivity at 20 °C
ε = 8.9–11.1 (anisotropic) [1]