Slight deviation between GIA and appraisal

[iploya]

Hi,

Different variations of this basic question have been posted by other users regarding other stones, but I just want to get some opinions on my particular circumstances.

Bought a GIA-certified stone, reported as .80, IF, G color, no flourescence, triple-excellent. I can provide the # by PM if need be, but let's start with the basics.

Took it in for appraisal. Online reviews for this guy very good. He has a small shop that ONLY appears to have lab equipment for appraisals; I did not see or hear about anything for sale, so no reason to suspect bias.

Stone was mounted. In looking under magnification, he confirmed the GIA#, then searched long and hard for imperfections, and finally thought he saw something tiny, so was about to give it a VVS1 I think. I asked him to re-check; he steamed it several more times, looked again, and finally deferred to the IF rating as reported.

Next, he compared to standard reference stones for color. His initial hunch was "I", and then hesitantly toward "H." I then told him it was graded as "G" and he wasn't sure. But the thing was mounted in a Pt setting. He finally put down G on the appraisal, deferring to the GIA report, but didn't seem 100%.

Q: how likely is it that the Pt setting made it read a shade or two darker, from G to H/I range? He said that difference was minor, but in monetary terms it's about $1000+ difference from the source. Is it significant enough to have it un-mounted and re-appraised?

Thanks

 

[slg47]

Hi,

Different variations of this basic question have been posted by other users regarding other stones, but I just want to get some opinions on my particular circumstances.

Bought a GIA-certified stone, reported as .80, IF, G color, no flourescence, triple-excellent. I can provide the # by PM if need be, but let's start with the basics.

Took it in for appraisal. Online reviews for this guy very good. He has a small shop that ONLY appears to have lab equipment for appraisals; I did not see or hear about anything for sale, so no reason to suspect bias.

Stone was mounted. In looking under magnification, he confirmed the GIA#, then searched long and hard for imperfections, and finally thought he saw something tiny, so was about to give it a VVS1 I think. I asked him to re-check; he steamed it several more times, looked again, and finally deferred to the IF rating as reported.

Next, he compared to standard reference stones for color. His initial hunch was "I", and then hesitantly toward "H." I then told him it was graded as "G" and he wasn't sure. But the thing was mounted in a Pt setting. He finally put down G on the appraisal, deferring to the GIA report, but didn't seem 100%.

Q: how likely is it that the Pt setting made it read a shade or two darker, from G to H/I range? He said that difference was minor, but in monetary terms it's about $1000+ difference from the source. Is it significant enough to have it un-mounted and re-appraised?

Thanks

is there a laser inscribed number on the diamond?

i'm not surprised about discrepancies given that the stone is mounted.

 

[iploya]

Hi, yes - that's what I meant by GIA number - the laser inscription matched. Thanks.

 

[iploya]

Others agree? Is a "G" going to look like an H or I when mounted in a generic 6-prong "Tiffany" style 950 Pt setting? Thx.

EDIT: Also, the GIA report says 61.2 depth, 57 table, 6.02 x 5.97 x 3.67 mm, and rates the cut as excellent. His initial measurements (again, taken while mounted) were slightly different than the GIA numbers, and his initial estimate was only "GOOD" cut. I know it's harder to take measurements while mounted, but the fact that I couldn't get a definite confirmation also bugged me a little. The gap between good and excellent is another $1000+.

 

[OCgirl]

I have an AGS graded G and when I took it to the appraiser (already mounted, 18kt white gold setting), the appraiser said "in between a G and H. Given that many here says AGS is slightly more lenient on colors but harsher on clarity. The appraiser commented my stone can pass as a GIA VS2 even though it's graded AGS SI1.

I am not sure if grading a mounted stone can affect the color grading. I'd be interested to know.

 

[diamondseeker2006]

The GIA report is going to be more reliable since the stone was loose. I wouldn't worry about it for a second. The main reason an additional appraisal is even useful (on a new stone) is to verify that the stone is the one in the report. Plenty of stones are borderline between one color and the next, so even GIA and AGS might grade the same stone 1 grade different.

 

[denverappraiser]

Yes the mounting, or a tiny amount of dirt under a prong can add enough apparent color to make a G look like an H when it’s mounted. That’s why the big labs refuse to grade stones mounted.

The GIA grading report is an important piece of the value of the stone, it’s NOT just a report of an examination. This is the cause of some infighting in the appraisal community because it’s a bit counterintuitive and it’s directly opposed to what GIA teaches but it’s really quite obvious. A stone ‘certified’ by GIA as a G/IF will cost more than that very same stone with a H/VVS1 pedigree. A 'high G' does NOT generally cost more than an otherwise similar 'lucky G'. There are some differences in the goods but the act of GIA saying it is where the extra $1000 comes from. If that’s not adding value I don’t know what is. If you’ve got a GIA graded stone and the appraiser can both confirm that it’s the correct stone for the report and that it’s undamaged, it’s entirely appropriate to reference the grading directly to the GIA and include a copy of the GIA report as supporting evidence.

 

[Modified Brilliant]

I would like to have the daily advantage of grading unmounted loose diamonds in an ideal laboratory environment but
for real world everyday appraising at the consumer level...I just have to cope with grading mostly mounted diamonds with all of the hidden inclusions, large prongs, sunken bezels, depths not visible, metal reflection, etc.

Not as easy as it looks!

However, I must say that laboratory graders would probably have a hard time grading mounted diamonds.

On the other hand, appraisers who grade everyday (Neil, Dave, myself and others) can grade BOTH loose and mounted diamonds with accuracy. We might not get it right 100% of the time...but we will be close...verrryyy close.

 

[oldminer]

I just purchased an additional set of 5 GIA blessed official Master DIamonds for color grading. They were reviewed by GIA in 2007 so they are rather recent compared to most in the hands of fellow appraisers and gemologists. The stone GIA graded as G is definitely a high F color. I have a recent GIA graded F color diamond, not one of the set, that is way darker than F color. For sure, it is a G color at best.
The GIA is not considered biased or other than objective about color grading, but subjectivity and obviously other issues are involved in the way the Gem Trade Lab part of GIA grades for its commercial clients. The gemologically educated part of the trade, a minority, has primarily depended on the GIA for its education and many of the grading tools, such as these Master Diamond sets. Yet, there is a good sized gap between our fervent hope and belief that GIA is somehow "perfect" in an imperfect world, but it just isn't the case. You can expect small differences of opinion on the color of diamonds from one gemologist to another. When the GIA does its very best for us, it is not anything like 100% repeatable grading. Pass this on one or two levels down to independent practicioners and an increased amount of grade spread has to occur.

One major issue which appears to be coming to light in the studies I have been part of for the past dozen+ years is that there is an inconsistency in grading diamonds which are not pure yellow in hue. Once a diamond has brown content, the grading is just not the same. The eyes perceive brown, and every other hue, differently and it is very difficult to transition from yellow hue master diamonds to grading brown diamonds. If the darkenss, the tone, of diamonds dictated the grade it would be easier to grade all colors simply by tone, but this is not the way GIA does it. We have to mimic their approach or results.

The conclusion, "expect inconsistencies".

 

[WishfulThinkingOne]

On the other hand, appraisers who grade everyday (Neil, Dave, myself and others) can grade BOTH loose and mounted diamonds with accuracy. We might not get it right 100% of the time...but we will be close...verrryyy close.

What exactly is accuracy? +/- 2 grades?
I don't see how grading faceup could ever be compared to how GIA grades color which is facedown and looking at the body.

I will assume you try to grade a mounted diamond upside down and looking at the body for "consistancy" with GIA but I fail to see how you could claim any kind of precision or accuracy as compared to GIA and their tightly controlled method with multiple independant graders on an unmounted stone.

 

[OCgirl]

What causes the color grading to be "worse" when it's mounted (aside from the possibility of dirt trapped in between the prongs...etc)? Because 18kt white gold/platinum has a color tone to it?

 

[Modified Brilliant]

On the other hand, appraisers who grade everyday (Neil, Dave, myself and others) can grade BOTH loose and mounted diamonds with accuracy. We might not get it right 100% of the time...but we will be close...verrryyy close.

What exactly is accuracy? +/- 2 grades?
I don't see how grading faceup could ever be compared to how GIA grades color which is facedown and looking at the body.

I will assume you try to grade a mounted diamond upside down and looking at the body for "consistancy" with GIA but I fail to see how you could claim any kind of precision or accuracy as compared to GIA and their tightly controlled method with multiple independant graders on an unmounted stone.

I'm not comparing myself to a diamond grader in a GIA lab. After looking at thousands of diamonds in thirty-plus years in this business after a while, you just develop a trained eye in dealing with color comparisons and what GIA graded stones look like.
If you are performing a repeatable task in any trade for a long period of time--you just gain more experience and accuracy as you go forward in time. Perfect accuracy? Absolutely not. Consistently close accuracy? Absolutely possible.

There will always be inconsistencies as Dave pointed out..I'm just saying that an appraiser can possibly be accurate most of the time +/- one color grade. Just my opinion. Even unmounted diamonds graded in a laboratory environment will not always have the same outcome.