Examples of different grading by GIA for same stone???

[AndyDiamond]

My appraiser mentioned that he has seen inconsistent grading from GIA as well, particularly he feels that their lab in India is more lenient. Anyone agree with that? Also, he said he has seen inconsistent grading by GIA when the same stone was sent back to GIA blindly to be regraded, and he mentioned seeing examples posted on Pricescope. Would someone please kindly direct me a link if available? I can't seem to find it.

Thanks.

 

[denverappraiser]

One of the things GIA has become extremely good at is recognizing when the same stone is submitted twice, even when it's at 2 different labs and even if they are submitted years apart. It's very unusual to resubmit a stone and get a different grade for this reason. They are humans and humans do make mistakes but it's the exception, not the rule. When stones are recut they can't do this and there is significantly more variability although I think it has more to do with WHEN the stone was graded rather than where. I have a nagging suspicion it also has something to do with who submits the stone.

 

[AndyDiamond]

How do they know if the same stone is submitted twice if there is no inscription of the previous report # on the girdle?

 

[denverappraiser]

How do they know if the same stone is submitted twice if there is no inscription of the previous report # on the girdle?

They're smart. You can do it with lasers and reflections ala gemprint (www.gemprint.com) and you can do it by using a computer to compare each and every measurement from their Sarin equipment (www.sarin.com). There are more. GIA is HUGE and they have a nearly unlimited budget. They call their system Horizon, and it's a proprietary thing to them developed at significant expense and held as one of their trade secrets but I'm 100% confident in their ability to do this. I have similar confidence in every other major lab in the world by the way. Heck, I'm a tiny one-man lab and even I can do it.

 

[Dreamer_D]

I know of two examples of this. My former 1.67ct was graded J by AGS and when resubmitted came back an I color. I think Diamonseeker's H was regraded and came back G, cannot recall if it was GIA or AGS.

 

[AndyDiamond]

I know of two examples of this. My former 1.67ct was graded J by AGS and when resubmitted came back an I color. I think Diamonseeker's H was regraded and came back G, cannot recall if it was GIA or AGS.

Why did you and Diamondseeker send it back to the same lab for grading? Just as a test?