I am aware that the AGA has posted up a presentation entitled: Tanzanite: Facts, Fears, Fakes that attempts to discredit our Tanzanite Trepidation articles that we have published over the past year. There are three issues regarding this presentation that need to be put forth:
1. The AGA presentation has taken a shotgun approach to the topic and covers issues that we never claimed, distracting from the real issues, such as things like “grain boundary diffusion,” “irradiation” and “indigo.” These are not anything we have mentioned with regard to possible tanzanite treatments, nor do we believe they are occurring.
2. The AGA presentation offers no research of its own, and it does not reflect the results of any actual testing. The report merely shows photos plucked from various sites around the web, which are then juxtaposed next to ISG photos with captions that claim the pictures prove us wrong. In fact, the photos AGA offers as evidence depict nothing that is relevant to the issues raised in the ISG reports.
3. The AGA presentation has carefully side-stepped the real issues raised by the ISG, such as that of growth tubes being filled with some type of purple filler material. This is the crux of the matter, much as it was with the so-called "Paraiba-like tourmaline" where LA-ICP-MS testing proved the material to have been color treated. This is the central issue of the ISG reports, and the AGA presentation did not bother to address this.
The real problem is that the ISG has proven that this material is NOT a reflection in a photograph, thus the AGA presentation falls flat on its face.
In an effort to get proper answers for the industry and consumers, the ISG has commissioned a tanzanite study, using LA-ICP-MS, by a respected independent scientific laboratory that specializes in this type of testing, in order to get a complete elemental analysis of these tanzanites so that there will be definitive proof of treatment.
Below are three images demonstrating the purple filler material in the tube. First is the tube material showing the abrupt end to the material in the tube and color flowing out from the tube area. Next is a close up of the tube showing the abrupt end to the material on one end. Below this is the area on the right side of the tube enlarged, clearly showing that this is not a reflection but rather some type of purple material in the tube.
Below, and in the banner of this edition, is a new image taken on 16 July 2013 showing an enlarged growth tube in a Thai sourced tanzanite. The green color is polish material in the opening of the surface-reaching growth tube. Further down this tube, however, is purple material seen to be flowing out into the gemstone. For this reason we believe that further and proper scientific investigation is warranted before this situation is considered resolved.