Exellent polish + Excellent symmetry = ?

[CountryBoy]

I've often read here that excellent polish and excellent symmetry does not equal an ideal cut. Having said this, I did a PS search of GIA Ex/Ex and then went to the corresponding website that was selling the diamond. In pretty much every case, the diamond was listed as ideal or signature ideal, and the HCA score was always less than 2.0.

A PS vendor has offered to sell me a few different GIA ex/ex stones that doesn't have the sarin info (or other cut info) and states that a GIA ex/ex is pretty much going to always be ideal.

So what am I to believe? Is there a substantial chance that a GIA ex/ex will be less than ideal? Or is my research and the word of the PS vendor accurate?

 

[belle]

the chances are good that the stone is indeed ideal. as a prudent customer,however, i would confirm the parameters for which the vendor considers a stone as ''ideal'' and then decide if you want to proceed.

 

[strmrdr]

Exellent polish + Excellent symmetry = by itself nothing.

It is an indication that the cutter may have taken the time to do the diamond right and it might be very nice.
But then again it could be a total dog.

The cutters of the top grade stones shoot for id/id ex/ex because it goes with the top cut and likely sells faster.

 

[Garry H (Cut Nut)]

GIA''s new cut grading system wil allow an Excellent grade to have VG Sym and Pol.
Each overall grade can have a grade lower in S&P (S&P= Finish in all the new grade systems).

AGS were going to do the same, but some politics kicked in. Even so in their system S&P carries less weight than it did in lower grades.

 

[Dancing Fire]

Date: 7/10/2005 5:00:33 PM
Author:CountryBoy
I''ve often read here that excellent polish and excellent symmetry does not equal an ideal cut. Having said this, I did a PS search of GIA Ex/Ex and then went to the corresponding website that was selling the diamond. In pretty much every case, the diamond was listed as ideal or signature ideal, and the HCA score was always less than 2.0.

A PS vendor has offered to sell me a few different GIA ex/ex stones that doesn''t have the sarin info (or other cut info) and states that a GIA ex/ex is pretty much going to always be ideal.

So what am I to believe? Is there a substantial chance that a GIA ex/ex will be less than ideal? Or is my research and the word of the PS vendor accurate?

the PS vendor shouldn''t have any problem getting you that info.i would think.

 

[mkb]

Triple X (Excellent) indicates an excellent grade in symmetry, polish and proportions.
As strmrdr correctly states an X for symmetry and polish by itself doesn’t mean much.
Triple X has very tight proportion specifications and is automatically Hearts & Arrows and Ideal (I am not American, I assume that by ‘ideal’ you mean the cut that Lazare Kaplan introduced in the late 80’s)
luc

 

[Garry H (Cut Nut)]

Date: 7/10/2005 10:59:40 PM
Author: mkb
Triple X (Excellent) indicates an excellent grade in symmetry, polish and proportions.
As strmrdr correctly states an X for symmetry and polish by itself doesn’t mean much.
Triple X has very tight proportion specifications and is automatically Hearts & Arrows and Ideal (I am not American, I assume that by ‘ideal’ you mean the cut that Lazare Kaplan introduced in the late 80’s)
luc

Welcome MKB.

You are obviously well educated.
But not so well informed.

AGS 000 means D IF ideal cut as well as the more known idea of tripple cut ideal
But Ags 000 for light performanc, proportion factors and finish does not mena the stone is H&A''s
And H&A''s does not mean the stone will be even AGS 3

 

[mkb]

Date: 7/10/2005 11:50:56 PM
Author: Garry H (Cut Nut)

Date: 7/10/2005 10:59:40 PM
Author: mkb
Triple X (Excellent) indicates an excellent grade in symmetry, polish and proportions.
As strmrdr correctly states an X for symmetry and polish by itself doesn’t mean much.
Triple X has very tight proportion specifications and is automatically Hearts & Arrows and Ideal (I am not American, I assume that by ‘ideal’ you mean the cut that Lazare Kaplan introduced in the late 80’s)
luc

Welcome MKB.

You are obviously well educated.
But not so well informed.

AGS 000 means D IF ideal cut as well as the more known idea of tripple cut ideal
But Ags 000 for light performanc, proportion factors and finish does not mena the stone is H&A''s
And H&A''s does not mean the stone will be even AGS 3

Thank You Gary,
You may be right in the ''informed part'', we mostly work GIA and HRD, I''m not familiar with AGS O. I will do some homework.

 

[Paul-Antwerp]

Hello Luc,

It has been ages since I last saw you. How are you doing, my friend?

Welcome on Pricescope. Garry is right, there is a lot of relatively new information to catch up with. But here is a great place to start learning.

Live long,

 

[mkb]

Hi Paul,
Am fine thanks, sitting in the middle of India it is hard to keep up with the new trends. I remember Leo telling me once that he used to visit this site. I''ll get back up to speed. People are pretty open on this site.
Nice hearing from you.

br
luc

 

[Garry H (Cut Nut)]

Hi,
I am a stones throw from the Gateway to India

 

[mkb]

Hi Gary,

I sent you a private message, we could perhaps meet up

luc

 

[Regular Guy]

Date: 7/10/2005 5:00:33 PM
Author:CountryBoy
I've often read here that excellent polish and excellent symmetry does not equal an ideal cut. Having said this, I did a PS search of GIA Ex/Ex and then went to the corresponding website that was selling the diamond. In pretty much every case, the diamond was listed as ideal or signature ideal, and the HCA score was always less than 2.0.

A PS vendor has offered to sell me a few different GIA ex/ex stones that doesn't have the sarin info (or other cut info) and states that a GIA ex/ex is pretty much going to always be ideal.

So what am I to believe? Is there a substantial chance that a GIA ex/ex will be less than ideal? Or is my research and the word of the PS vendor accurate?

Generally I'll defer to the experts here, but I think you're missing the substance of Country Boy's question, and should recognize that he's done some homework here. Although excellent polish and symmetry may not be factors that, by themselves, guarantee anything, in the same way that JohnQ at WF indicates that they have arrived at a protocol for categorizing non-in-house diamonds offered in their web site, based on a number of known factors, I presume these particular factors play into their assigned formula. Further, I'll bet the good old boys at GIA had been using, with a measure of success, those factors to do not too wacko analysis of the quality of a stone, because they are in fact, as a pattern, also associated with the quality of a diamond's cut, just as Country Boy has sought to do a study of this correlation.

After all, if it were not for the reasonableness of a correlation, the criticisms leveled at HCA (you have to see the stone to know anything) would have merit, although i will grant you not only the lack of important causal correlation is there, and also, exactly as Belle says, rather than rely on the odds or percentages of a likely well cut diamond, Country Boy, I would want to have an exact measure to get the ducks in a row; if your PS vendor can't help, I'd recommend using a resource like one of the on-board independent appraisers who might assist you with that.

Crazy? I'd ask for Feedback, but really, Country Boy has already done this. Again, the question he's asked can only be answered, I think, by some data analysis, and not by looking only at what polish and symmetry can determine, in and of themselves.

With regards,

 

[CountryBoy]

Just wanted to thank all who replied to my query. I was able to get the vendor to provide me with a Sarin report, and despite the Ex/Ex ranking from GIA, the stone did not have good preportions and came out very poorly on the HCA software. Upon further experimentation, I''ve found several GIA Ex/Ex that appear to be off in cut. An unusually high pavillion angle seems to be the usual culprit. I know the way a diamond actually looks is most important, but when you are in a small town in a small state doing your purchase via the internet, numbers seem to be important.

Oh well, back to the grindstone. I''m going to find the right diamond at the right price if it kills me!!

 

[Regular Guy]

So, even if I''m the only one who learned something here, thanks for your diligence in following through.

Regards,