Tanzanite And Some Imitations

Zoisite: Blue to violet
Tanzanite (trade name)
R.I=1.688 – 1.696 (1.691 – 1.700); Birefringence=0.008 – 0.009; S.G=3.35

Heavy Pb-Glass
U.M Tanzanic (trade name)
R.I=1.600 – 1.605; Birefringence= Isotropic (SR); S.G=3.36 – 3.48

YAG
Purple Coranite (trade name)
R.I= >1.80; Birefringence= Isotropic (SR); S.G=4.58

Synthetic Corundum
Blue Coranite (trade name)
R.I=1.764 – 1.771; Birefringence= 0.007; S.G=4.02

YAG
Russian YAG (trade name)
R.I=>1.80; Birefringence= Isotropic (SR); S.G= 4.56

Ca-Phosphate Glass
R.I=1.537; Birefringence=Isotropic (SR); S.G=2.64