Fluorescence and Tiffany Cert vs. GIA

Rock,

1. Tiffany claims that their certification is more stringent than the GIA evaluation. Does anyone have any experience that this is the case?

Tiffany lab has a good reputation for consistency and they use the same scale as GIA does, at least for clarity and color.  Stringent isn't really the correct word but they rarely get accused of overgrading stones.  They are a fine lab. I wouldn't worry about them and, if they promised you a GIA report, I think you can be confident that it will both arrive and be as described.  As I understand it, they only give the GIA report if you ask so make sure they understand that you want it.

2. Where can I find a table with the GIA 'Ideal' parameters? I've found one online for AGS, but not for GIA.

GIA doesn't use a cut grading system in the same way that AGS does. There are no 'ideal parameters'. 

3. The Tiffany cert. on Ring #2 said the Symmetry is 'Very Good', the Polish is 'Very Good', and Precision of Cut is 'Excellent'. Would you expect that the GIA cert would show 'Excellent' across the board, assuming the Tiffany cert. is more strict? What does it mean if these characteristics are only 'Very Good' vs 'Excellent'. Ring #1 was 'Excellent' across the board.

The scale is Poor-Good-Very Good-Excellent.  I would not make assumptions about how one lab would grade a stone based on the report of another lab.  Look at the GIA report and see.  GIA does not have a category for Precision of Cut.

4. Fluorescence. Ring #1 said 'Faint' on the Tiffany cert. Ring #2 said 'Medium Blue' on the Tiffany cert. Again, would you expect the GIA cert to say something different? What does it mean to have 'Medium Blue' fluorescence on an E color ring and am I worrying about nothing?

Most people don't object to either faint or medium fluorescence although there has been quite a bit of discussion on the forum about it.  Use the search box near the top right corner of this page to search for 'fluor' and you can see what people have had to say on this topic.

Neil Beaty
GG(GIA) ISA NAJA
Independent Appraisals in Denver

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