This gem was faceted from an unheated piece of tanzanite–most tanzanite has been heated to remove the orange-brown and greenish-yellow components to make the gem a dark blue to purple-blue. In this gem there was a zone of violet-blue and zone of green–they both show in the finished gem. As the gem is held in the hand you can see the zones of violet and blue-green for an unusual bi-colored effect. It also changes color–under incandescent light the gem appears to be a zoned with purple and blue.
I faceted this tanzanite in the classic diamond round brilliant design. There are a few tiny inclusions visible in the macro image, but they are not visible in the hand without a loupe. The gemstone weighs 1.58 carats and measures 7.3 x 4.7 mm.