White Sapphire

White sapphire is colourless corundum — the same mineral as blue sapphire, with the colour-causing trace elements absent. It is a 9 on the Mohs scale, which makes it the most practical diamond alternative there is.

It does not have diamond's dispersion, so it reads as a soft, watery white rather than a sparkle. In a well-cut stone that is an advantage: the light stays in the stone instead of scattering off it.