My hope to contribute something to the forum - Tiffany Gemological Report Rounding

[Tiff1886]

Thanks for all your help so far in my quest to find a "near super ideal" Tiffany Modern Round Brilliant.

After searching through a couple hundred gemological reports online - I think I may have empirically determined how Tiffany rounds their angles and percentages on their reports. These are just my guesses based on observation - Tiffany doesn't tell us. We also don't know how many measurements they take before they average them, and round them.

I looked at a ton of reports and saw how much each measurement typically varies (in decimal points). If I saw one stone with an angle measurement of 34.5 and another with 34.6 - then I would eventually conclude they report out to one "tenth" of a degree (0.1). After seeing several reports with "adjacent" measurements, I started to see the level of resolution they report out to and built the table below.

I only post this in hopes that it helps someone in the future if they are set on a Tiffany modern round brilliant. I modeled the table to match the rounding section in the education portion of the PriceScope website.

Major Proportions	Tiffany Gemological Report
Table Facet	1%
Crown Angle	0.1 degree
Pavilion Angle	0.1 degree
Girdle Thickness	Description
Cutlet	Description
Minor Proportions
Star Length	1%
Lower Half Length	1%
Upper Half Length	Not Reported
Calculations
Total Depth %	0.1%
Crown Height %	0.1%
Pavilion Depth %	0.1%

 

[headlight]

It was my understanding that Tiffany diamonds are now accompanied with a GIA report which, of course, follow their rounding practices. If true, that is interesting if the Tiffany report may have slightly different proportions.

 

[Tiff1886]

It was my understanding that Tiffany diamonds are now accompanied with a GIA report which, of course, follow their rounding practices. If true, that is interesting if the Tiffany report may have slightly different proportions.

Historically, they included a GIA report. In recent times, they only include their own "Tiffany Gemological Report."

In some ways it is good - the resolution provided on the angles and percentages is higher than the GIA report.

In other ways it is bad - although Tiffany is known to be very trustworthy, it is still not an independent report. It does not include any information on light return or optical symmetry (via ASET, etc).

 

[Bonfire]

In recent times, they only include their own "Tiffany Gemological Report."

When I was in Tiff’s a few months ago, I brought up the question about GIA certification. My SA (very nice woman) ”schooled” me that their own certification was superior

 

[DejaWiz]

When I was in Tiff’s a few months ago, I brought up the question about GIA certification. My SA (very nice woman) ”schooled” me that their own certification was superior

If the findings above are indeed correct, then I'd be inclined to say that Tiffany may closely mirror the AGSL averages and rounds... unfortunately, we don't know if Tiffany also closely mirrors the stricter AGS0 criteria for cut quality.
Possible, I suppose.