Beautifully mastercut tanzanite with fully reflective cutting.  Royal blue plus violet color.  Certificate says if heated or not cannot be determined.   I suspect like most all tanzanite unless yellow brown or greenish it has been heated.  Very pretty stone.   Because of the rectangular shape of tanzanite crystals rounds are much more difficult to find because of the greater loss when cutting.   This is why ovals and rectangular cushion cuts are most prominently available.  Because of this greater lost in cutting for rounds there is normally a premium.   I try to eliminate this and try to give best prices.  

This stone is loupe clean or close.  I searched with a loupe and a torch light but all I noticed were dust particles that wiped away from the surface.   I called it VVS as I don't like to overstate a stones quality.   This is a clean stone at 10X.

Tanzanite from Tanzania where all tanzanite comes from.  The only place in the world.  When heated to 750 to 900 F or 400 to 500 C the brownish tints vanish and the tint of blue deepens.  I have read all Tanzanites is heated.  If they say it is not they are mistaken.  Gemologist cannot tell as it can happen naturally in nature and there fore is accepted as if it was not heated.  From what I read ALL Tanzanite is heated.