Beautiful blue tanzanite.   Loupe clean.   IF quality at 10 power.   Extremely clean looking when viewing with jewelers loupe.  10 x internally flawless it looks to be upon examination.  Very reflective stone.  No apparent window which is often seen in tanzanite cut stones.  

Round cut tanzanites are more rare because of the rectangular crystal shape of the rough crystal and the added waste upon faceting rounds.
Certificate is online verifiable using the square through the photo function of your camera. It automatically brings up the certificate through the website.
When heated to 750 to 900 F or 400 to 500 C the brownish tints vanish and the tint of blue deepens.  

Before heating the stones are trichroic which means three different colors depending on the direction you are looking at the stone.  After heating the stones become dichroic which is two different colors.  The best of the best is royal blue when viewing down at the face of the stone.  Some tanzanites show royal blue from all directions.  I try to take tweezer videos and photos but I'm scared to drop the stone and I take my shots outside.  This one kept twisting in the tweezers and I didn't want to chance dropping it.  I'm not the best at taking videos or photos.
This stone is masterfully cut without window.  Full reflection.