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 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 blue and green for an unusual bi-colored effect. It also changes color–under incandescent light the whole gem appears to be a light violet color.
I faceted this tanzanite in my custom “Triptych” trillion 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 2.57 carats and measures 8.5 x 5.6 mm.