This is a natural tanzanite with excellent blue, purple dichroism. The luster is superb, glassy, and top quality. It has also exceptionally well-formed faces and is complete all around, 360 degrees. This specimen, for quality of aesthetics, is hard to beat in this price and size range! Note also the gemminess...there is substantial cutting and facet rough value here. The matrix at the bottom perhaps acts to squelch the red c-axis color that might otherwise be present in natural tanzanites...for some reason that third color is not present here, but at the same time I am sure the crystal is not treated due to the shade of each hue (the purple would disappear and go blue in a treated crystal).