Answer: The following excerpt appeared in our online newsletter GIA Insider, Volume 1 Issue 4, on Wednesday, November 24, 1999 in the GIA Insider Gemologist Section. "Since 1991, rumors have circulated that Russian scientists were manufacturing synthetic tanzanite. Though it has yet to be documented and is definitely not commercially available, the buyer must still beware, for there are several tanzanite imitations currently on the market. In 1996, Gems & Gemology reported on the following three tanzanite imitations: (1) man-made glass marketed as U.M.Tanzanic, (2) blue synthetic sapphire marketed as Blue Coranite and (3) purple YAG (yttrium aluminum garnet) marketed as Purple Coranite. For the gemologist, these imitations were easy to detect because their gemological properties - most importantly optic characters, refractive indices and specific gravities - differed from those of tanzanite. In 1999, a more convincing imitation hit the market - synthetic forsterite. Like tanzanite, blue synthetic forsterite is highly pleochroic, exhibiting blue and purplish pink colors in polarized light. Because it also has the same optic character and sign as tanzanite (biaxial +), the best way to separate blue synthetic forsterite is by its refractive indices 1.635-1.670 (compared to tanzanite's 1.69-1.70). For more details, see the Winter 1996 and Summer 1999 issues of Gems and Gemology."

GIA insider also published an article entitled What Are the Identifying Characteristics of Tanzanite, and How Is It Distinguished from Imitations?

Our quarterly journal Gems & Gemology, has published several interesting articles about tanzanite simulants over the years. The following references discuss these simulants:

"More Soviet synthetics", Spring 1991, p. 55
"Tanzanite-colored synthetic sapphire", Fall 1995, p. 215-216
"A convincing tanzanite substitute", Summer 1996, p. 138-139
"Synthetic spinel and glass triplets ("Tanzation")", Winter 1996, p. 289-290
"High R.I. glass imitation of tanzanite", Winter 2003, p. 317-318

If you are interested in reading any of these articles, you can purchase a back issue from Gems & Gemology online, or contact our subscriptions department at (800) 421-7250, ext. 7142 or e-mail: dortiz@gia.edu.