This is the Burma spinel I got from AJS Gems under darkroom illumination with my LED light source from my microscope, and a portable blacklight for a UV-A light source.
You can see how the stone appears naturally before turning the UV light on. Then you can see how it turns to a brown color as if it were absorbing the light. When the light goes off, it’s a dark brown color. However, it does gradually obtain its color back in time. There is no sign of phosfluorescence, and there is a total lack of fluorescence thus indicating it is a Burma spinel.
The orangey red variety from Mogok mine has a very high absorption rate within a window of the latter range of IUV to the lower end of VIS. I obtained a general graph of how spinels of different colors from Mogok behave under IR spectroscopy, and the graph shows the absorption rate of spectra within the lamp as being highest. A vivid red spinel is slightly less. There was no information available for spinels from Tanzania, but it’s a tell tale indicator of origin.
