White Sapphire, Colourless Corundum

White or colourless sapphire is pure corundum, aluminium oxide, without the trace elements that make its coloured varieties: it is the same species as ruby and blue sapphire, differing only in the absence of chromium, iron or titanium. At hardness 9 it is second only to diamond, exceptionally durable, and has long served as a diamond substitute, more convincingly than glass or cubic zirconia because it is a genuine hard natural gem, though it lacks diamond's fire owing to lower dispersion. Much white sapphire on the market is heat-treated to remove a faint tint.

In Indian jyotisha colourless sapphire is used as a substitute for diamond, the gem of Venus, Shukra, when diamond is beyond reach, a recognised practice within the navaratna tradition. Beyond that its symbolism is thin and largely borrowed; modern metaphysical writing assigns it general themes of clarity and the higher centres on the basis of its colourlessness.