Tanzanite question

[Mayacamas]

Hello,

Before I was a devout pricescope reader,about a year ago I was bitten by the Ebay bug and bought a Tanzanite that is 4.9 cts cushion cut and has a huge window in it!!!!!!!!!!!!!

I didnt know then.....

I really like the color and would like to get the stone bezel set - but I now know enough to know I have to get it recut. I am unafraid of loosing carat weight to get rid of the window- as it sits in a drawer and I am not wearing it!

1. Can someone recommend a gem cutter who will recut Tanzanite?

2. Can someone show me some pendants with large Tanzanites?

Thanks!!!!!!!

Maya

 

[valeria101]

Sure you know the two or three cutters around here

It would be interesting to see this one...
Windows appear when a stone is to shallow (or cut with a flat bottom in luckier cases) so recutting to get rid of the window completely may end up into a significantly smaller stone. There aren''t too many cures to this, but fancy crowns (checker or something else that gets rid of the table facet) or concave facets on pavilion (those seem to provide good light with shallower pav angles) may help. As far as I know, not many cutters handle a wide range of exotic styles though.

 

[Michael_E]

HI Maya,
Typically windowing is caused by the cut of the stone being too shallow. In general you need at least 60% to 65% depth to minimum width in order to avoid windowing. If you could post the length, width and depth of your stone, and hopefully a picture showing the pavilion, then it would be possible to give you an idea of how it might be re-cut so that you lose as little size as possible. Usually what happens is that it can be re-cut to leave the length alone and just cut the stone a bit narrower. The good news is that tanzanite cuts and polishes easily, so the cost for re-cutting is less than it would be for a sapphire, for instance.
I would also make sure to ask your bench jeweler if they feel that they can bezel set that stone in the mounting you like without damaging it. Some thick bezels need to be tapped into place and you don''t want to tap anywhere near a tanzanite, as they chip easily.

 

[Mayacamas]

I dont have a great way to post photos, but here is the verbal description:

Unmounted bulge sided rectangularshaped mixed scissor faceted tapered moderately bright moderately saturated strongly bluish medium purple measuring 11.56 x 8.25 x 5.95 weighing 4.56 cts.

I will try to do some photos with my camera and post.

Thanks
Maya

 

[Mayacamas]

Okay

Here are some crummy photos I hope they help

 

[Mayacamas]

another

 

[Mayacamas]

another

 

[Michael_E]

Maya,
The way that I''ve got this figured is that you have plenty of depth to completely avoid any windowing. This is when the stone is face up with your line of sight perpendicular to the table of the stone. Since tanzanite has a low refractive index it will start to window on the pavilion side opposite you with as little as 5 gegrees of tilt. This is to be expected and there is nothing that can be done about its tilt brilliance. However if you are seeing a window with the stone face up, then what has happened is that the cutter has increased the "bulge" on the sides of the stone causing a steeper angle next to the girdle and an angle towards the culet that is too shallow. This is done to make the stone heavier and therefore "worth" more. The remedy is to recut the pavilion sides so that the angles at the very bottom of the stone are at least 40 degrees and then adjust the bulge from there. This will not cause any reduction in size, but it will cause a loss of weight...I''d guess maybe .4 carat at the most. You say that you are afraid of losing carat weight, why? The idea behind jewelry, for most of us, is in the wearing and display of it. How it looks matters more than carat weight. If it concerns you too much, you could always mount it as-is. The color is great and even with a window it probably still looks great when it''s moving around.

 

[Blue Eyes]

http://www.concavegems.com/


Richard Homer is a trusted and highly decorated cutter with a lot of Pricescope followers .. myself included. Do a search on him on PS and you''ll see before/after of his work with examples of tanz re-cutting.

He is both a skilled artisian and a classy gentleman who is a joy to work with.