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60-60 Rule?


daddysgirl
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Hi again. I'm almost ready to purchase my diamond. I saw a diamond rated a premium cut on jamesallen.com, but when I looked at the GIA report it rates it as excellent. Does that just mean that the girdle falls into the excellent parameters? It looks like a great diamond -- I just love the fact that they put those pictures up there. Is it okay to buy a diamond with a 59 percent table and a 60.4 percent depth? I know that the table is just outside the ideal cut. Polish is vg and symmetry is vg with no flouresence. Thanks for your help. This has been a work in progress now for four months. I've ordered my ring in platinum to fit a 1.25 to 1.50 diamond. Is four prongs okay? Denise

Edited by daddysgirl
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Hi again. I'm almost ready to purchase my diamond. I saw a diamond rated a premium cut on jamesallen.com, but when I looked at the GIA report it rates it as excellent. Does that just mean that the girdle falls into the excellent parameters? It looks like a great diamond -- I just love the fact that they put those pictures up there. Is it okay to buy a diamond with a 59 percent table and a 60.4 percent depth? I know that the table is just outside the ideal cut. Polish is vg and symmetry is vg with no flouresence. Thanks for your help. This has been a work in progress now for four months. I've ordered my ring in platinum to fit a 1.25 to 1.50 diamond. Is four prongs okay? Denise

 

 

Which exact stone are you looking at? Premium cut sounds like just a rating that is determined by a website using numbers. GIA doesn't use that terminology.

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Jan, I know GIA doesn't use a premium rating. James Allen uses ideal, premium, good. The report says it's an excellent cut. I was just wondering what exactly that means when they rate a cut excellent. Does it mean ideal? I don't think it can because the table is too large for an ideal cut. Thanks, Denise

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Hi Denise,

When the seller assigns a name to cut of their diamonds, it's very misleading. There's no way to say anything specific about what that seller calls a premium cut, or a good cut. The terms are meaningless.

The fact that GIA called the cut excellent, is the only meaningful classification of the cut of that diamond.

As such, we can assume that the diamond is very very well cut. There's nothing wrong with a 59% table or 60.4% depth.

 

You mentioned that you have ordered your setting. I would not do that, until you to select your diamond. In fact, my suggestion is that you buy both the setting and the diamond from the same seller. This can avoid a lot of potential problems that come from buying the setting and diamond from separate places.

 

It is commendable for any seller to have actual photos of the diamonds they sell-but that does not mean that they possess the diamonds.

A single photo, in black and white is not all that descriptive. I'd like to see more photos to get some better perspective.

For example, here is a photo from our website.

178r2302c.JPG

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Denise,

 

GIA’s cut grading scale is complicated. Many call it ridiculously complicated. They took a few hundred thousand observations of a few hundred stones that they knew quite a bit about and asked people which ones they liked. They then ranked the stones into 5 general categories based on their popularity in the study. Yours is most similar to the stones in the top 20% of popularity in that study. Excellent is their top grade.

 

Play a little bit with the tool at www.facetware.gia.edu. It's free and it gives some level of idea how the various attributes relate to come up with the cut grade.

 

‘Ideal’ is another word they don’t use. That comes from the AGS system, which is a complicated thing on it’s own right. No, a 59% table would not make a stone ineligible for an AGS ideal grade with their current system but it may do so on someone else’s scale. There is some out there that would get both AGS-ideal and GIA-excellent but they are not identical and there are plenty that would get one or the other but not both.

 

Call up James Allen and ask them these questions. ‘Premium’ is a grade that they assigned and they should be prepared to explain what they mean by it.

 

Neil

Edited by denverappraiser
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Jan, I know GIA doesn't use a premium rating. James Allen uses ideal, premium, good. The report says it's an excellent cut. I was just wondering what exactly that means when they rate a cut excellent. Does it mean ideal? I don't think it can because the table is too large for an ideal cut. Thanks, Denise

 

 

It's probably not ideal then if the table is too large. AGS uses the ideal cut grades.

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Hey everybody!

Neil, I was wondering- did AGSL change their standards for what constitutes an ideal cut in 2006 when gia came out with their cut grade system?

 

Good point, it would be a great idea to call up the seller and discuss the stone with them.

 

Neil, you mentioned that the GIA cut grading scale is complicated. To me, it seems quite simple for the end-user. I really couldn't see any diamond that garnered a GIA "excellent" cut grade being a dog.

Of course, GIA's cut grade is much broader the old AGSL "ideal"-. There are certainly buyers looking for parts and arrows, and for them, the specifications are more narrow.

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AGS changed to the ‘performance’ based system and abandoned their old charts in 2005. This is what GIA was reacting to when they came up with theirs. I put performance in quotes because it’s not really a direct measure of the performance of the stone. It’s done by raytracing a computer model. I think it’s a good system and actually I like it considerably better than the GIA approach (which is also done by analyzing a computer model by the way) but I think the name is a bit misleading.

 

No, I’ve never seen an undamaged GIA-excellent that I would describe as a dog, at least not because of the cutting, but some are definitely better looking to me than others. There are also some GIA-VG’s and even a few GIA-G’s that are really quite lovely. 90% of the stones seem to be in these top 3 GIA grades and a significant majority, say 75% are in the top 2 (Very Good and Excellent). As a shopping tool for people who are trying to use it to differentiate the wheat from the chaff without actually looking at the stones this makes it less than optimum.

 

Have you been through one of the GIA classes or bought the lab manual on how to do it? It's complicated.

 

Neil

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I agree Neil I've seen diamonds graded "very good" that looked awesome.

Do you really think that 75% of all round stones GIA grades are the top two grades?

 

 

I think the folks at GIA would disagree with what you term them reacting to something as opposed to their position, which would likely be, that they took a long time to come up with a system that they feel works.

Personally, I never liked the old AGS system-I've always loved well cut diamonds that had 60% table and 60% depth. Diamonds of these proportions were not considered "ideal"-I always felt that that in itself proved the term proprietary. That is to say "Ideal Cut" became a brand.... the word no longer had the same meaning as the word ideal does in the English language.

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Do you really think that 75% of all round stones GIA grades are the top two grades?

 

Yes. Something tells me that the real production stats on this are a closely held secret at the lab.

 

I think the folks at GIA would disagree with what you term them reacting to something as opposed to their position, which would likely be, that they took a long time to come up with a system that they feel works.

 

I'm sure you're right. GIA isn't keen to admit to be reacting to outside influences or acknowledge that there is gemological research going on outside of their control and 'leadership'. Then again, I'm an AGS guy. B)

 

Personally, I never liked the old AGS system-I've always loved well cut diamonds that had 60% table and 60% depth. Diamonds of these proportions were not considered "ideal"-I always felt that that in itself proved the term proprietary. That is to say "Ideal Cut" became a brand.... the word no longer had the same meaning as the word ideal does in the English language.

 

I agree. Apparently so does the gemological sciences committee at AGS. They did change the system after all.

 

Neil

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Jeez, so much info. When I ordered my setting he said that anything from a 1.25 to 1.50 would be fine. The head is a four-prong set which can accommodate that size stone. I am getting very frustrated at James allen because I ask for photos and then none are sent and they're not on their website yet. I spoke with the jeweler about that issue and he assured me that it would be fit the size stone I'm looking for. I'm tired from shopping all day for a table and we're still not moved back into our home. Thanks all. Talk to you soon. Denise

I'll check out your website.

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Hey everybody!

Neil, I was wondering- did AGSL change their standards for what constitutes an ideal cut in 2006 when gia came out with their cut grade system?

 

David you remember correctly. AGS no longer gives range limits; the parameters are judged all-together.

 

It has been a breath of fresh air to 60/60 lovers (know anyone like that?) B) because many diamonds with 60% tables now qualify as AGS Ideal as long as they have appropriate performance values. In fact, diamonds with tables from 47% to 62% can now theoretically earn AGS Ideal depending on how all 57 facets work together.

 

It's actually a stricter system than the old one, just more mature as it doesn't 'cut off' diamonds for going over a line in any one parameter...it's looking at how all the parameters work together.

Edited by JohnQuixote
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