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Sapphire

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

General

Category

Oxide mineral

Formula

Aluminium oxide, Al2O3

(repeating unit)

Identification

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

nε=1.760–1.763,

Birefringence 0.008

Pleochroism

Strong

Melting point

2,030–2,050 °C

Fusibility

Infusible

Solubility

Insoluble

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]