How often does AGS and GIA misgrade color?

[Jj08]

I was doing some research and found the thread regarding Harriet''s I colored stone that was most likely mis-graded by AGS. I was enthralled. It got me thinking and I was wondering if the experts and appraisers could chime in and give us an idea of how often this has happened in their careers? If at all? And if so, how bad? 2 color grades? I know it''s all subjective but how can one be off by so much, as in Harriet''s case?

Jj08

 

[blasimon]

This should be helpful if you haven''t seen it already...

 

[Jj08]

No I haven''t seen it. Thank you.

 

[oldminer]

In theory, the GIA is the owner of the standardized color comparison grading system we have used for years with diamonds. Because of this the GIA is never, or virtually never, theoretically, wrong with their color grading. While the GIA does make the occasional boo-boo they are the keepers of the sytem and what they say tends to be taken as a fact, when it truly is just an expert opinion. Nearly all the time the GIA is right, in my opinion, and rarely could I "prove" the GIA is incorrect by virtue of providing "factual evidence". I might disagree with their grade from time to time, but am I more credible than the GIA? Which expert among us can claim greater credibility than the GIA Gem Trade Lab? It would be a useless battle even if we believed we could possibly do a better job. It is an imperfect system and the further one gets away from the mother master color set, the more error potential is possible.

Labs like GIA or AGSL very infrequently err in color grading. I am sure they have made slightly off color grading decisions on rare occasions. Especially in the F to K range, a grade error of 1 to 2 grades away from a correct grade can just "happen". It may be fluorescence throwing off the grader, incorrect light tubes, incorrect distance to the light tubes, the poorer than acceptable vision of the non-GIA grader. It could be more sinister, such as deal pressure, but I am sure such would be a VERY rare case although it might happen. D-E color discrimination seems relatively easier for labs as there is little room to find gray areas of crossopver color range. Below K, the color grade is of far less importance and each color has a wider zone range. One grade off below K might be more common, than 2 grades off and the price differential is not huge anyway.

A main issue is a problem with the extra narrow range of I color. Once this gets fixed "someday", the system might be more reliable.

 

[Rockdiamond]

I think it''s important to remember that the colors are actually ranges.
The range of D color is far narrower than that if J color. If the range from D to E could be represented graphically, let''s say it''s an inch.
The range from the bottom of H to the top of J ( I color) would be about a foot, using this representation.

There will be stones on the fringe that may fall either way. These are stones that may get I color one day, and J color the next day.

GIA has a method for dealing with this: re-checks.
If someone disputes the color ( or clarity) grade on a GIA report, they can re-submit for a re-check.
If GIA does not change the grade, you pay 1/2 the price of the original report.
If GIA does change the grade, there is no charge.

We have submitted many stones for re-check, and I''d estimate about 1/3 have the grade changed.