Synthetic corundum
is colorless in the absence of dopants. This is the tip of a large
boule pulled from molten Al2O3 contained in an iridium
crucible.
Synthetic corundum
is colorless in the absence of dopants. This is the tip of a large
boule pulled from molten Al2O3 contained in an iridium
crucible.
Synthetic ruby colored
by Cr3+
Natural sapphire
from Brazil colored deep blue by Fe2+ and Ti4+ intervalence
charge transfer