The Hard Facts of Sapphires and Rubies Ganoksin Jewelry ...
Diffusion treatment is another method that adds color to corundumusually sapphire, although diffusiontreated ruby can be found on the market in small amounts. The treatment consists of packing colorless or lighthued faceted sapphires or rubies in powdered chemicals that naturally cause the color of corundum; a blue sapphire, for example, might be packed in titanium oxide.
