What is a diffusion sapphire?

Diffusion sapphire is a natural sapphire that has undergone some type of diffusion process in order to alter or improve its appearance.

Diffusion treatment of sapphires is used for both natural and synthetic stones in order to improve the quality of color. This kind of treatment is irreversible. The essence of the method consists in the artificial chemical diffusion of sapphire as a result of heating in a medium with a composition that causes a change in color at the structural level. In most cases this coloration is of a near-surface character and can be eliminated by means of re-cutting (and even re-polishing). But some methods of diffusion can cause a change in the entire stone.