Sapphires treated by lattice diffusion generally cost less than sapphires that have been treated by heat without the addition of color-causing chemicals or sapphires that have not been treated.
Lattice diffusion is a treatment process that uses heat and chemicals to diffuse an element into a gemstone to artificially change its color. Lattice diffusion treated sapphires can be any color. In some cases the added color is shallow. In others, it goes all the way through the stone.
SPECIFIC GRAVITY: 3.95-4.03
REFRACTIVE INDEX: 1.762-1.788
HARDNESS: 9(Hardest after Diamond)