GIA finds Titanium-Coated Tanzanite

[Karl_K]

I did a google search and didn't see this posted so thought I would post it.
Apologies if it was already posted.
http://www.gia.edu/gia-news-research-titanium-coated-tanzanite-cooper

 

[pregcurious]

Thanks, Karl, I have never heard of this. I recently became aware of titanium diffused star sapphires. Looks like someone has been busy with titanium.

 

[lambskin]

Where in the world would the coating be applied? It must happen after the stones are cut. Would the cutter know that the stones would be treated for enhancement purposes? How would the coating be applied? Certainly, not a lot of suppliers have titanium sitting around and the sophistication to apply it. Any thoughts?

 

[chrono]

An article about this was released on Rapaport in 2008 so it's not new but word has not spread far and wide about this coating yet. It sounds very similar to the same titanium coating applied to the pavilion of topaz, thereby creating mystic topaz. Therefore, I presume this is done after the tanzanite has been cut. It appears to be highly difficult to detect in larger tanzanite which is disturbing to me, especially if it requires highly specialized equipment such as the LA-ICP-MS. I suppose the original colour is amped by the coating, which makes it harder to detect unless the pavilion facets are worn enough to allow bits of its true colour to show through.

 

[Karl_K]

Where in the world would the coating be applied? It must happen after the stones are cut. Would the cutter know that the stones would be treated for enhancement purposes? How would the coating be applied? Certainly, not a lot of suppliers have titanium sitting around and the sophistication to apply it. Any thoughts?

Since its a coating it would be applied after it was cut.
There are several different process that can be used, I am not sure which one would work for this.
The processes are not that uncommon and the equipment not hugely expensive.
Once could set up a dedicated coating operation for around $20k-$50k or so.
More than likely they would just contract it out to someone who has the equipment and it wouldn't likely be more than a few dollars each in small lots and cheaper in large.