Normal for slight difference between GIA report & Sarin

[tawn]

I just noticed that there is a slight difference on my diamond between the GIA numbers and the Sarin. Which would be more accurate? I''m assuming that it would be the Sarin....Is that common for the numbers to be a little different?

GIA report shows, Depth 61.1% & Table 56%

With the Sarin report the diamond scores 1.3 on the HCA, but if I use the table & depth from the GIA report it scores 1.1! Either way it''s a good score right!?

 

[SeaOats]

Either way the score is fine.

And yes, it is normal for the numbers to differ slightly.

 

[tawn]

That''s a relief....I didn''t even notice they were different until yesterday and then I started obsessing!

 

[denverappraiser]

Tawn,

GIA uses Sarin equipment to measure their stones.

Sarin advertises their accuracy to be within 0.02mm. This is with multiple readings of the same stone on the same machine. Variations between machines can be a little more than this because of calibration issues so yes, it''s fairly common to have slight variations.

If you are going to be using the various dimensions on the Sarin report that aren''t included on your GIA report, like the crown and pavilion angles, use the sarin report for everything. GIA''s numbers are probably slightly more more reliable but by using some numbers from one machine and some numbers from another you are adding an unnecessary variable. Even if there is a slight callibration error, it''s going to be the same general error on all measurements.

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

 

[tawn]

Thanks Denver guy...

Another quick question...when I use the GIA numbesr with the Sarin %''s, I actually get a 1.1 HCA, and a little box with the AGSO shows up! What exactly is that??

I probably should have figured all this out before I bought the stone!!

 

[denverappraiser]

The little box is the boundary of crown and pavilion measurements for a particular table size (listed at the top) in order for a stone to be eligible for the AGS zero cut grade using the old AGS scale. The X is the location of the values that you entered. AGS has recently modified their system a bit and the HCA is still using the pre-July 2005 rules so it’s not all that good an indicator of what AGS would call the stone but they’re still a pretty good set of parameters. The AGS cut grading system is discussed in the tutorial and in tons of the threads in the forum.

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

 

[Garry H (Cut Nut)]

Leonid is putting the new AGS candidates on the charts any day now