Can a GIA Cert be wrong?

[Jobo]

Hi

I was wondering if someone out there can give me some advice.

I am looking for a stone for my engagement ring (my boyfriend said if I procure it, he will finance it!) and I have fairly well settled on a round brilliant F (eyeclean) SI1 around 1.00ct.

I have found what seems to be the perfect stone!

I have seen photos at 30x magnification, have seen a short film of it being moved around in front of a camera to show scintillation, and the ideal scope image shows very little to no white light leakage. I do agree that the stone seems exceptionally bright. But, I have not seen the stone in person as it is on the other side of the country.

The stone is also a really good price. Not stupidly cheap, but probably around $800-$1000Aus cheaper than any others i have seen. I have also seen the GIA Certificate dated late this year.

The only problem is that the stone is rated with a ''Very Good'' Cut grade on the certificate and this guy is telling me that this particular stone is better than what is stated on the certificate.

He says that he has run it through his OGI meter and it has come out with an ''ideal'' rating.

See below the values. The original number is the GIA Cert, the number in brackets is from his cut report.

Crown Angle: 34.5 (35)
Pavil Angle: 40.8 (40.9)
Table Size: 54 (54.5)
Depth: 61.7 (61.9)
Cutlet: 0 (0.4)
Girdle: Vthin-Sl thk Faceted (Sl Thk)

I have run them both through the HCA and they have both come out with scores under two.

I have spoken to this guy at length several times, he has been very helpful (seems trustworthy) and is offering a 30day money back guarantee.

Is this a great buy? Or should I hold out and pay the extra for an Excellent cut?

Cheers

 

[Rhino]

There are elements beyond the basics here that can contribute to the GIA VG grade. It may be excessive painting or excessive digging which would/could impact both the cut grade and the optical beauty of the diamond. While the HCA is helpful it is by no means exhaustive for determining a cut grade or diamond beauty even with seemingly great numbers. I have seen and am familiar with the differences from the Ex to VG grade so my professional opinion would be to hold out for an Ex (preferably that also falls into the AGS ideal zone as well) as those constitute the rarest and most beautiful.

*edited to add* ... while the painting/digging *might* be an issue I see the girdle thickness you've listed is "v-thin" which means there is a part of the girdle GIA deems too thin to make its Ex grade. If this is the only issue then it would really depend on how much of the girdle is actually "very thin" and if that area is exposed and succeptible to further chipping or not. If just a small area that can be covered with a prong then it may not be such a bad thing. If you can post the MegaScope report perhaps we can see from the girdle graph just how much is "very thin".

In answer to the original question however ... GIA can sometimes be wrong. Humans are doing the job and we are all prone to error from time to time.

Peace,

 

[Jobo]

Hi Rhino

Thank you for your advice.

I have attached the Cut Report and Idealscope and Aset image that they gave me.

Can you please explain what you mean by digging/painting.

Also, I am really after the best stone that I can get for my budget. I really only want to pay for things that make the stone look as best as it can. If this truely is a stone that could fit into and excellent grading due to its beauty, then is it worth paying for a certificate/

Thanks again

 

[Jobo]

Sorry...Here is the Idealscope and Aset image.

 

[Garry H (Cut Nut)]

Rhino is on the money. Very thin will get the downgrade, but the scan you posted does not help (neither does the mickey moouse Ogi bar chart)
From the ASET the stone has been painted - is it an 8*?

That could be the reason - and in that case there will be a note to say something like grade affected by brillianteering in comments.

Give us the report # and ct wt and we can give you more info
Or it could be the

 

[denverappraiser]

The OGI is using the word ‘ideal’ to describe the set of parameters on your list that have a ‘0’ to the right of them. This is not the GIA methodology and they don’t translate well from one system to the other. Different labs and different tools will use different definitions for their various scales and OGI’s version of idealness contains some stones that GIA or AGS will call something different. I agree with the above that the v.thin girdle will kick you out of the excellent category. There may or may not be other things as well but you don’t have (and probably can’t get) the raw data that GIA used. Although GIA does have an appeals system if you or your jeweler would like them to reconsider one of their grades, it rarely works out and, as an individual, it gains you very little. It won’t make the stone any more beautiful no matter what they say. Talk to your jeweler about the possibility of a durability problem involving the girdle as this may have an affect on how you plan to set the stone.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[oldminer]

In the USA the GIA is in the strange or fortunate position to never be wrong. Some people may disagree with any grade GIA issues and occasionally the GIA will change a grade based on a customer''s appeal. When you are on top of the mountain, or on top of the heap, the only direction you can go, if anyone moves you, is down. While it must be wonderful to be on top, the danger exists from all sides and there is only one way to go if you move.

I believe there is a small, but growing, agreement in the trade attacking the supremacy of the GIA Lab mostly in criticism of its CUT grading strategy. This eventually may move the GIA to a less enviable position. The GIA should be looking at the looseness of its current round cut grading and also be looking to adopt similar cut grading for fancy shaped diamonds.

 

[Jobo]

HI

Unfortunately I am looking at buying this stone online and do not have access to any other data than that provided.

I did speak to the seller of this diamond and he indicated that it was a very bright stone and had been incorrectly (or harshly) graded by the GIA and that due to the cut report reading only ''very good'' I would be able to buy it at a very good price.

He didn''t mention to me anything about girdle that may have been detrimental when I asked (because I did ask him to clarify the v thin to Sthk on the GIA Report) and told me it was exceptionally bright.

I am still unsure of what painting is (is that something to do with its ''exceptional'' brightness), and unless I ask for a more detailed cut report I am guessing that I will never know why it didn''t make the Excellent grade.

But from your advice, it seems that this may be a stone that I should stay away from due to inconclusive information.

Can I count on OGI information in the future though? Is this more accurate than the GIA Grading system?


Thank you

 

[Jobo]

Gary

WHen you say report number, do you mean GIA Cert Number? 16406774

Cut Wt according to GIA Report says 1.00Ct and dims are: 6.42-6.48 x3.98mm

Also, my Idealscope turned up in the post yesterday and I have been checking out all my diamond earrings and bracelets. Can I just say, the lack of pink on those stones tells me that I got ripped....

Me smarter now though....

 

[JohnQuixote]

Jobo, you''re talking about the same thing (''cert'' and report). The reason Garry and other experts refer to these as grading reports is because ''certificate'' is technically incorrect.

The Very Thin girdle is enough to cause this diamond to get VG in cut instead of EX. Click here for its results from GIA report check. Some of the numbers are a little bit different from OGI, which is to be expected - because of GIA rounding and possibly some scan error within normal tolerances.

 

[Garry H (Cut Nut)]

Date: 12/17/2007 2:56:12 AM
Author: Jobo
Gary

WHen you say report number, do you mean GIA Cert Number? 16406774

Cut Wt according to GIA Report says 1.00Ct and dims are: 6.42-6.48 x3.98mm

Also, my Idealscope turned up in the post yesterday and I have been checking out all my diamond earrings and bracelets. Can I just say, the lack of pink on those stones tells me that I got ripped....

Me smarter now though....

You probably did not get ripped off since very very few stones pass the ideal-scope test, you got normal.

Nothing wrong with the data on that GIA report

F SI1 is my pick of color clarity cost benefit