Since at least 1995, various materials have been manufactured to imitate tanzanite in the gem trade. These include two glasses, two different YAGs (yttrium aluminum garnet), and a synthetic corundum. These imitation tanzanites can be readily separated from the natural gem by standard gemological tests, such as refractive indices, optical character, specific gravity, UV-visible spectra, fluorescence, and the presence or absence of pleochroism. The identifications were confirmed by chemical analysis and Raman spectroscopy.
