In early 2006, GIA made a series of changes to the format of their grading report. They started to assign cut grades for round brilliant diamonds and included data on proportions (crown angles, pavilion angles and etc).
This revamp in GIA’s grading report format subsequently caused huge changes to the role a Sarin report has in the market.
Now, you might be wondering what’s the difference between a lab report and a Sarin report? In a nutshell, the GIA certificate contains averaged measurements of a diamond’s proportions instead of individual measurements found in a Sarin report.
For example, instead of showing 8 separate values for crown angles, the GIA report simply shows an averaged number for these readings. Likewise, this applies to other measurements like the girdle thickness, pavilion angles and etc… The beauty about this revamped report is that it contains sufficient data for consumers to make purchasing decisions without being too overwhelming.
Still, there are some situations where it is better for you obtain a copy of a Sarin report. One such scenario happens when you intend to purchase an old estate diamond graded before 2006. It is advisable for you to get a Sarin scan performed so that you have the necessary cut proportions for analysis. Ultimately, my recommendation for dealing with such purchases is to get the stone sent to GIA for a re-grading.
Question: If diamond proportions had already been included in a grading report, why is there a need for a Sarin scan of the diamond?
Answer: In my experience of viewing diamonds and verifying lab reports, I had personally found many discrepancies in diamond proportions measured by labs like EGL and IGI.
As a precautionary measure, it is wise to request a Sarin scan if you are buying non-GIA/AGS diamonds. You basically want to have this additional information to back up the cut details that is listed on the report.
Note: I only recommend AGS and GIA as they are the most reliable labs in the world.
Typically, proportions and angles provided in AGS reports were found to be spot on. On the other hand, GIA applies a slightly different methodology when displaying their measurements. Due to the rounding and averaging of numbers, you might get variances when you compare their results to that of an actual Sarin scan.
Since the GIA reports only show averaged measurements, there will be subtle differences in cut properties between 2 diamonds even if they have similar specifications on their GIA certificate. These minor differences can sometimes decide the fate of serious chunks of money and that’s where a Sarin report would be useful.
For example, a Sarin scan would not only reveal the overall relationships of the facets, it would also provide in-depth details of how each facet meet at their points.
2 sample reports from JamesAllen.com
Based on the 2 reports above, which diamond do you think is cut to better precision? If you guessed the first stone, you are right. Smaller tolerances shown in the first diamond is evidence that the cutter took greater care in creating proper facet alignments.
On the corresponding GIA report for the first diamond, the crown angles are rounded up to the nearest 0.5° and simply shown as 34.0°. Likewise for the second diamond, the crown angle is reported simply as 34.5° on the GIA report. With an average of 8 measurements and subjecting the final number to rounding, a 34.0° crown measurement could mean a lot things. Now, do you see why there are certain limitations to a GIA grading report?
Although it is generally true that a diamond has better brilliance when it is cut to better precision, there are times where having precision doesn’t necessarily translate to having better optics.
The light performance of a diamond is largely influenced by proportions. For example, even if a diamond has very tight tolerances of less than 0.1° for all 8 of its pavilion angles, it wouldn’t matter if the facets are cut to a steep 45.0°. Being precisely cut with bad proportions will still result in a dull and lifeless looking diamond.
To conclude, a Sarin report is a useful tool for people who want to assess a diamond analytically since it can show you minute details. However, if you don’t want to deal with a string of confusing numbers, getting an Idealscope/ASET image is the easier way for you to perform critical cut evaluation.<< Prev Page