Confused on what exactly is Ideal cut...Help!

[devientdrow]

When we purchased my diamond last Christmas I thought I had a good handle on what was Ideal cut. I knew that other cut diamonds could look great too but when searching for the BEST cut out there I wanted an Ideal cut diamond, which meant it fit into the parameters of the HCA? I might be using the wrong term there, but I had these Ideal porportions printed out and used them as a guidline. Now I also know that there were AGS graded diamonds that were called triple 0, which from what I understood meant that they were Ideal cut as well as the best in Polish and Symmetry. Now the diamond I was looking at located at Smyth was an AGS000. I found that I was able to find a diamond online at James Allen, slightly larger and cheaper. I saw it and it looked just as good to me, better even that it was larger. Now my diamond I was told is Ideal Cut. Graded by GIA. On the package he has printed out AGS0, which i''m guessing all his packets have that for an Ideal cut diamond. Mine is a .83ct round brilliant and these are the other dimensions:

Measurements: 6.09-6.13x3.71mm


Depth: 60.7%
Table: 56%
Girdle: Very thin to Medium, Faceted
Cutlet: None
Polish: Very Good
Symmetry: Very Good

This is all the info I have on this one. Is my diamond truly Ideal cut? And with all this new talk of AGS grading will it always be considered the top of the line cut wise? or will that change?

Also what the difference between stones like hearts & arrows or ACA? Are they BETTER than an Ideal cut diamond?

I''m confused.....

 

[belle]

there is no way to know what kind of cut you have without at least crown and pavilion angles.
no stone can be ags0 unless it has the grading report. especially with ''very good'' in polish/symmetry. part of the ags0 designation comes from the finish grade (p/s).
h&a stones (including the brand aca) are diamonds with superior optical symmetry. diamonds with top optical symmetry have been shown to perform better than those without.

 

[aljdewey]

Date: 8/17/2006 12:09:35 AM
Author:devientdrow

When we purchased my diamond last Christmas I thought I had a good handle on what was Ideal cut. I knew that other cut diamonds could look great too but when searching for the BEST cut out there I wanted an Ideal cut diamond, which meant it fit into the parameters of the HCA? I might be using the wrong term there, but I had these Ideal porportions printed out and used them as a guidline. Now I also know that there were AGS graded diamonds that were called triple 0, which from what I understood meant that they were Ideal cut as well as the best in Polish and Symmetry. Now the diamond I was looking at located at Smyth was an AGS000. I found that I was able to find a diamond online at James Allen, slightly larger and cheaper. I saw it and it looked just as good to me, better even that it was larger. Now my diamond I was told is Ideal Cut. Graded by GIA. On the package he has printed out AGS0, which i'm guessing all his packets have that for an Ideal cut diamond. Mine is a .83ct round brilliant and these are the other dimensions:

Measurements: 6.09-6.13x3.71mm


Depth: 60.7%
Table: 56%
Girdle: Very thin to Medium, Faceted
Cutlet: None
Polish: Very Good
Symmetry: Very Good

This is all the info I have on this one. Is my diamond truly Ideal cut? And with all this new talk of AGS grading will it always be considered the top of the line cut wise? or will that change?

Also what the difference between stones like hearts & arrows or ACA? Are they BETTER than an Ideal cut diamond?

I'm confused.....

"Ideal cut" to most people means that the diamond has cut proportions that qualify it for the top cut grade offered by a grading lab.

Before GIA unveiled their version of a cut grade matrix, it most often anecdotally meant that a diamond's cut proportions would fit into the tight parameters that would earn an AGS0 grade.

However, under the old AGS system, the proportions alone weren't enough to earn the AGS0 for grading. It also had to have Ideal Polish and Ideal Symmetry. So, under the older AGS0 cut system, your diamond wouldn't have made AGS0 because of the VG/VG, but it may have still had cut proportions that fell into the cut-proportion parameters. It's hard to know because you don't have the crown/pavilion angle info.

When GIA unveiled it's cut system and AGS revised its grading system, things changed. Around here, the seemingly prevailing sentiment of many is that GIA's EX grade is softer than the more stringent AGS0 cut-grade. The AGS cut grade depends on more than just measurements now; it also grades light performance.

GIA doesn't actually call their top-graded stones "ideal"....they call them "Excellent." Unfortunately, the term "ideal" has come to be utilized as a generic descriptor, which can be misleading. it's like calling a band-aid a band-aid. They aren't really band-aids, they are adhesive strips....but since everyone calls them band-aids, it's become a generic-type term.

Same thing. It's likely that you were told your diamond was an "ideal" cut as a way to tell you that it was among the finest makes of stone. However, it's not a true AGS0 stone unless it comes with AGS paper.

Oh, and regarding the HCA.....the HCA isn't a pass/fail way to identify "ideal" cut stones, and it doesn't bill itself as such. The HCA is a predictive tool that helps to eliminate a potentially poor performing diamond. That's all it is....it doesn't grade stones. It may show you where you stone's cut proportions fall relative to the best gradings offered by AGS/GIA, but it's not a substitute for those grading reports.

Please know that none of these "pedigrees" changes the way your diamond looks on the hand, so don't become disenchanted because someone has suggested that your A just turned into an A-. It's still likely among the most well-cut stones out there today and likely far better than the average stone on the street.

H&A means hearts and arrows....again, another non-regulated term, but one used to describe the precision of the hearts&arrows pattern exhibited by a diamond. Branded simply means someone put their logo on it as an endorsement that it meets his/her standards.

 

[devientdrow]

You know i''m actually quite upset now. It''s not that I don''t think my diamond is pretty, I do. I like it. But it was listed on the James Allen site as an Ideal Cut diamond. Thanks for the explanations guys! I knew the diamond couldn''t be technically AGS0 without being graded by AGS I just thought it might of been something they used to let them know which diamonds were "Ideal" and which ones weren''t. When I went to go see Jim he took the time to show me the diamond in different lighting...under the scopes ect ect. Really took the time out to show it all to me. I just looked up the GIA site for more info on my stone and this is what I found:

Crown Angle: 34.5
Crown Height: 15 %
Pavillion Angle:41
Pavillion Depth: 43%
Star Length: 55%
Lower Half: 85%
Cut Grade: Very Good

I mean this was graded in 2005 and thats not even an excellent cut

Why would he sell this to me as an ideal cut diamond?

 

[devientdrow]

Now i''m super confused...I looked in the Tools section http://diamonds.pricescope.com/round.asp doesn''t my stone fall under the "Ideal" proportions then? Why would it only be rated Very Good instead of Excellent?

 

[JohnQuixote]

DD - No reason to be upset. There are logical explanations.

1. Your depth, table, crown and pavilion angles do conform to traditional 'Ideal' proportions which AGS used prior to July 2005, so the stone was not misrepresented to you. For that matter, that combination is still predicted to qualify for the new AGS 0 'Ideal' mark in light performance (which is one of 3 factors which contribute to the overall cut grade).

2. It sounds like you already know this: With VG polish/symmetry this diamond would not qualify for the overall Ideal cut grade (sometimes called AGS000) then or now. This is not a performance concern; the difference between VG/EX/Ideal polish and symmetry is not visible, it's a matter of fine craftsmanship.

3. The issue is the girdle. GIA judged it as Very Thin - Medium. The 'Very Thin' is what reduces it from EX to VG: If the girdle was Thin-Medium it may have received EX (see attached graphic from GIA's facetware).

Without knowing more details I can't say whether the girdle would have received a penalty from AGS or not. Girdles which are judged too thin receive a penalty for durability. If the diamond has been safely set and worn regularly since Christmas it's probably fine. Did you get a Sarin report? It would tell us more about how thin the girdle ranges to.

On a separate note, for sake of accuracy, I'd just remind you that GIA rounds their reported numbers. This means your 41 Pavilion Angle may actually be a 40.9, your 34.5 crown angle may be anywhere from 34.3-34.7, etc. There is no way to know for certain without a Sarin, Helium or Ogi report.

My micro-analysis aside, it sounds like you have been happy with the diamond and got it for a nice price. I wouldn't lose sleep over the old ideal/new ideal/ex/vg of it all. The most important thing is how it looks to you.

I hope this explanation is helpful.

 

[JohnQuixote]

FYI: Bill Lieberum posted a similar thread about ''Ideal'' grading a few days ago.

https://www.pricescope.com/community/threads/is-your-stone-really-an-ags-000.49351/