Clarity: Eye clean
Origin Opinion: Tanzania
Cut: Mixed Portuguese cut
Price: £500/ct + Vat
The Heat Treatment of Tanzanite
Virtually all tanzanites are heat-treated to produce the beautiful blue-purple colours. There is a very small amount of unheated material but the stones tend to have secondary colouration (green). Tanzanite is very strongly trichroic and will display three colours depending on the orientation of the crystal. The correct orientation is imperative in the cutting process to achieve the best colours.
Warning: In recent years unsubstantiated claims have been made about treatments being performed by a process which was described as ‘dyefusion’. The rumours were propagated from a self styled gemmology school in the US and have never been accepted by any other gemmological organisation anywhere in the world. The author of these claims refuses to have his research peer reviewed by independent laboratories. Until these accusations are independently verified by respected gemmological laboratories they can only be considered as junk science. We therefore recommend you ignore all claims of tanzanite 'dyefusion' until there is confirmation of such treatment from a professional laboratory.
The Origin of our Tanzanite
All tanzanite is mined at the deposits in the Manyara Region of Northern Tanzania.