What Are White Sapphires?

White Sapphire Shape

• Gemologists classify corundum based in terms of how it naturally forms. Thus, white sapphires belong to the trigonal crystal system. The trigonal system features stones with three axes, or lines of symmetry, none of which are at right angles to each other.

Color and Luster

• White sapphires are completely colorless and, like sapphires in general, are classified with a vitreous. However, dealers can also classify stones that are mostly clear, that display a hint of color, as white sapphires.

Hardness

• As with other corundum varieties, white sapphires rate a 9 on the Moh's scale, a relative hardness scale on which diamond rates a 10 and talc rates a 1. This makes white sapphires qualify as what is currently understood as the second hardest natural mineral on Earth.

White Sapphire Refractivity

• When light passes through one substance to another substance with a different density, it bends. The angle that the light is bent depends on the difference in density between the two substances. This bending of light is known as refractivity.

  The science of faceting gems makes use of refractivity. People faceting gems work to create the proper amount of refracted light inside a gem. An index exists to define the level a gemstone refracts light, called the refractive index, or RI.

  The level of refractivity of white sapphire is considered to be good, though not as good, as a diamond, having a refractive index of 1.766 in comparison to diamond's refractive index of 2.417. Though rarer than diamonds, white sapphires are less expensive than diamonds. This results in white sapphires appealing to those who are looking for a clear, hard stone for jewelry, but who might have a budget too tight for a diamond Normally, though gem artists use white sapphires as accent stones.

Sources

• White sapphires are found in Australia, Burma, Cambodia, Thailand, Madagascar, Sri Lanka and Tanzania. The best of these natural sources is Sri Lanka. Natural white sapphires average in size from 0.06 of an inch to 0.10 of an inch in width, and may be heat-treated. Synthetic white sapphires are also available on the market.