Is 60/60 a bad proportion for a round diamond- can we trust a GIA "EX" cut grade?

[Serg]

Date: 2/19/2009 10:26:29 PM
Author: Garry H (Cut Nut)

Date: 2/19/2009 10:17:33 PM
Author:

I just want to make sure that people are aware that h&a refers to optical symmetry and not any certain set of cut numbers. You can have a poorly cut diamond with h&a optical symmetry. You can even have a '60/60' with h&a. You can have a well cut diamond without h&a. You need an h&a viewer to properly evaluate this.

i do not think you can have a H&A's pattern in any 60:60 combination.

David you have seen photo's of GIA Ex leakage (John posted it, taken on my hand so you can see my fingers thru the center of the stone).
You have also been linked to the article in the journal section here where there is series of articles about the mistakes GIA made, with repsonses from the GIA Cut Team, that you would never know existed because you have no desire to learn, only to keeep your witch doctor voodoo systems intact.

re

i do not think you can have a H&A's pattern in any 60:60 combination.

Garry,

Why? What is about P41.75Cr34.5T60GirdleValley1.5%
Did I miss anything in definition H&A( I hope we are speaking about generic H&A ) or in definition 60/60

I can not see real reason for such heavy fighting

60/60 is old rejection tool and selling tool. Effectiveness using this tool strongly depends from person skills . 60/60 is just first level of system filters .
High skillable person uses a lot of other filters ( girdle thickness , proportions, symmetry , final performance)

Of course you can easy do wrong selection , some sells persons actively used it( Used Brand 60/60 to sell bad diamonds)

But similar problems for IS. it is first level filter in more modern and effective rejection system. IS image can not guaranty high performance. Some sells persons can use IS Brand to sell really bad diamonds
Of course IS is more strict rejection tool and give less field for bad game

AGS0, H&A are more strict rejection tools

From one side more strict rejection tool give better guaranty to receive good diamonds( reject bad diamonds)
from other side more strict rejection tool have bigger chance to reject good diamonds.
Some person could be very proud to find good diamonds what are not AGS0. Its really unique , rare diamonds ( for real conouncer)


I really do not see technical reason for such heavy fighting .

57% table is modern “Ideal”
60% table is old fashion “ideal “

May be tomorrow 53% will “Ideal”
Of course what worst 60/60 is worse than worst AGS0. But much more interesting and helpful for understanding CUT to compare Best 60/60 with best AGS0


Could we change negative argue to positive competition ?

David,

Do you agree prepare best 60/60 for Open competition ? ( to compare best your 60/60 with 1)ASG0 2)best AGS0)?
Cut Group will prepare technical tools to write High resolution film both diamonds in same light conditions in exactly same trajectory of movement.

Then we will calculate flashes , grade brightness , performance.
We will not inform about connections between diamonds and movies before we finish grade . Anybody could vote

How is about real game? Could we do totalizator on PS ?

 

[Garry H (Cut Nut)]

Date: 2/20/2009 12:58:08 PM
Author: John Pollard

Date: 2/19/2009 7:27:20 PM
Author: Rockdiamond

...It''s so easy to assume that a GIA VG cut is not as nice looking as an GIA EX cut grade.
But there''s certainly a lot of amazing VG cut grade stones out there.
There are some people that would pick the VG cut grade stone in a blind test. The difference is by no means ''night and day'' to even a trained observer...

[Meant to reply to this earlier]

No doubt. I believe it has to do with the amount of obstruction GIA used. It’s unrealistic and, unfortunately, allowed some steep-deeps in while banishing combos in the 40.4-40.5 PA range to VG. That’s a whole ‘nother subject - and hopefully a revision in GIA’s future.

Actually John it was the DiamondDock seating position and viewer / diamond / light angle that set the GIA proportions that were selected.
https://www.pricescope.com/community/threads/gia-diamond-dock-simple-summary.42538/ this is a short 19 post discussion with easy to understand images.
I could do a cartoon version if it is over anyones head?

 

[Rockdiamond]

HI Everyone!

John, thanks for the Rappaport article- we know AGS like to use that type pf technology, but clearly, it''s not embraced by many people in this field.

Re: the GIA cut grade.
Garry , you, and others choose not to trust GIA.
I, and most other professionals in the trade do trust GIA.

For every expert John mentioned there are 10 who feel differently.

It is clearly stated here that "Steep Deep" is bad, yet there''s no photographic evidence of that. I have yet to see photos demonstrating the GIA EX cut grade with the "Ring of Death"- much less a real diamond that shows this.
I have offered to find a real diamond that meets these parameters, and photograph it. I will be glad to do that next week- if such a combination exists in real life.
My position is that what some are calling Steep Deep will be attractive to others- including a fair percentage of the over 70,000 human observations GIA used in designing the grade.


The diamonds and cutting styles you guys like can be lovely, but there''s other people who like other looks in diamonds.
Dancing Fire''s friend, for example.This wasn''t a young bride, who''d never tell her fiance she doesn''t love the diamond.
This was a guy who''d spent a ton of money- and already purchased earrings.
He chose to buy what many here call "badly cut steep deep diamonds"

I guess he has no idea what he likes, right?


In terms of the chart showing the 8 profiles of diamonds- if I knew how my responses were going to be used, I never would have responded at all.
I noted certain aspects of the cut which are visible form a side view. If asked to grade the cut of those CG stones based on profile views, I would not have done so.
Can anyone say that it''s possible to be able to grade the cut of those 8 simulated diamonds based on the info I had?

If I was selecting a diamond for my own personal use, I would not use ASET or IS.
Why are people so seemingly insulted and opposed to even discussing an alternative viewpoint?

I''m accused of "honking the horn louder", yet it''s me, and even our clients who are viciously attacked - simply because I''m expressing a different point of view.


As I mentioned before, I value the opportunity to participate here, and apologize if my views cause people any discomfort.

 

[Rockdiamond]

Date: 2/20/2009 2:45:24 PM
Author: Serg

Date: 2/19/2009 10:26:29 PM
Author: Garry H (Cut Nut)

Date: 2/19/2009 10:17:33 PM
Author:

I just want to make sure that people are aware that h&a refers to optical symmetry and not any certain set of cut numbers. You can have a poorly cut diamond with h&a optical symmetry. You can even have a ''60/60'' with h&a. You can have a well cut diamond without h&a. You need an h&a viewer to properly evaluate this.

i do not think you can have a H&A''s pattern in any 60:60 combination.

David you have seen photo''s of GIA Ex leakage (John posted it, taken on my hand so you can see my fingers thru the center of the stone).
You have also been linked to the article in the journal section here where there is series of articles about the mistakes GIA made, with repsonses from the GIA Cut Team, that you would never know existed because you have no desire to learn, only to keeep your witch doctor voodoo systems intact.

re

i do not think you can have a H&A''s pattern in any 60:60 combination.

Garry,


Why? What is about P41.75Cr34.5T60GirdleValley1.5%
Did I miss anything in definition H&A( I hope we are speaking about generic H&A ) or in definition 60/60

I can not see real reason for such heavy fighting

60/60 is old rejection tool and selling tool. Effectiveness using this tool strongly depends from person skills . 60/60 is just first level of system filters .
High skillable person uses a lot of other filters ( girdle thickness , proportions, symmetry , final performance)

Of course you can easy do wrong selection , some sells persons actively used it( Used Brand 60/60 to sell bad diamonds)

But similar problems for IS. it is first level filter in more modern and effective rejection system. IS image can not guaranty high performance. Some sells persons can use IS Brand to sell really bad diamonds
Of course IS is more strict rejection tool and give less field for bad game

AGS0, H&A are more strict rejection tools

From one side more strict rejection tool give better guaranty to receive good diamonds( reject bad diamonds)
from other side more strict rejection tool have bigger chance to reject good diamonds.
Some person could be very proud to find good diamonds what are not AGS0. Its really unique , rare diamonds ( for real conouncer)



I really do not see technical reason for such heavy fighting .


57% table is modern “Ideal”
60% table is old fashion “ideal “


May be tomorrow 53% will “Ideal”
Of course what worst 60/60 is worse than worst AGS0. But much more interesting and helpful for understanding CUT to compare Best 60/60 with best AGS0


Could we change negative argue to positive competition ?

David,

Do you agree prepare best 60/60 for Open competition ? ( to compare best your 60/60 with 1)ASG0 2)best AGS0)?
Cut Group will prepare technical tools to write High resolution film both diamonds in same light conditions in exactly same trajectory of movement.


Then we will calculate flashes , grade brightness , performance.
We will not inform about connections between diamonds and movies before we finish grade . Anybody could vote

How is about real game? Could we do totalizator on PS ?

THANK YOU Serg!!!
I was posting while you were- I so appreciate your post.
Yes I''d love to see a study of a really well cut 60/60 against a Near Tolk- that would be very informative to this conversation.

I don''t know if I can even find one- but I will try.

 

[Serg]

re:THANK YOU Serg!!!
I was posting while you were- I so appreciate your post.
Yes I''d love to see a study of a really well cut 60/60 against a Near Tolk- that would be very informative to this conversation.
I don''t know if I can even find one- but I will try.

David,


when you will find it, please inform us about diameter.

We need compare diamonds with exactly same diameter . I think you can easy spend 1-3 weeks to find best for you sample

My suggestion to All to start do real work, tests what can improve understanding, knowledge and avoid spent time just to fighting .

More facts, more correct tests, transparence test conditions . Then discussion about Results

 

[Postie]

Hi,

I''m looking at buying a diamond and have posted the specs of a couple I have my eye on.

Your inputs would be greatly appreciated

https://www.pricescope.com/community/threads/looking-at-buying-a-diamond-pics.107872/

 

[purrfectpear]

Date: 2/20/2009 3:12:15 PM
Author: Rockdiamond
If I was selecting a diamond for my own personal use, I would not use ASET or IS.
Why are people so seemingly insulted and opposed to even discussing an alternative viewpoint?

I'm accused of 'honking the horn louder', yet it's me, and even our clients who are viciously attacked - simply because I'm expressing a different point of view.


As I mentioned before, I value the opportunity to participate here, and apologize if my views cause people any discomfort.

Because all of those "alternative viewpoints" existed well before the creation of Pricescope. As Serg mentioned, 60 table is "old preference".

I don't think there is any valid reason for someone to "honk the horn louder" about information that is no longer considered the most current and accurate information.

You keep mentioning that lots of cutters and diamond dealers like other than AGSO type diamonds. Well sure they do. Somebody has to sell the stuff that doesn't pass AGS0 specs. You say customers like them. You're right there too. The majority of diamond consumers are not educated beyond a cursory glance at the "4-C's". That's why mall stores stay in business. We don't need to turn this forum into a place that validates that sort of stock. It's already available for those who want it.

I fail to see how Pricescope benefits from your proposed dumbing down of the technical aspects of evaluating diamond performance.

Correct me if I'm wrong, but you seem to espouse the "walk into the store (or online) and pick what looks pretty to you" method of purchasing. We don't need to promote that. Diamond customers have been doing it for years. Some pick winners, the majority picked average. B&M stores were thrilled to sell those average stones. That's NOT what Pricescope is about. It isn't about the masses, it's about those willing to educate themselves. Do you want to go to the pet store and pick the cute puppy, or do you want to research breeders, bloodlines, health certifications like OFA, CERT, and make sure that the litter you have selected from will yield the best possible conformation and health, and then pick the cutest one to your eyes?

 

[Rockdiamond]

Date: 2/20/2009 3:58:08 PM
Author: purrfectpear


Correct me if I''m wrong,

Purrfect, not that I believe you actually want me to correct you but yes, you''re wrong.
All due respect, but please don''t try to state my position.
You really do a poor job of it.


An idea that existed before Pricescope is not necessarily wrong Purrfect.

 

[Serg]

Date: 2/20/2009 3:58:08 PM
Author: purrfectpear

Date: 2/20/2009 3:12:15 PM
Author: Rockdiamond
If I was selecting a diamond for my own personal use, I would not use ASET or IS.
Why are people so seemingly insulted and opposed to even discussing an alternative viewpoint?

I'm accused of 'honking the horn louder', yet it's me, and even our clients who are viciously attacked - simply because I'm expressing a different point of view.


As I mentioned before, I value the opportunity to participate here, and apologize if my views cause people any discomfort.

Because all of those 'alternative viewpoints' existed well before the creation of Pricescope. As Serg mentioned, 60 table is 'old preference'.

I don't think there is any valid reason for someone to 'honk the horn louder' about information that is no longer considered the most current and accurate information.

You keep mentioning that lots of cutters and diamond dealers like other than AGSO type diamonds. Well sure they do. Somebody has to sell the stuff that doesn't pass AGS0 specs. You say customers like them. You're right there too. The majority of diamond consumers are not educated beyond a cursory glance at the '4-C's'. That's why mall stores stay in business. We don't need to turn this forum into a place that validates that sort of stock. It's already available for those who want it.

I fail to see how Pricescope benefits from your proposed dumbing down of the technical aspects of evaluating diamond performance.

Correct me if I'm wrong, but you seem to espouse the 'walk into the store (or online) and pick what looks pretty to you' method of purchasing. We don't need to promote that. Diamond customers have been doing it for years. Some pick winners, the majority picked average. B&M stores were thrilled to sell those average stones. That's NOT what Pricescope is about. It isn't about the masses, it's about those willing to educate themselves. Do you want to go to the pet store and pick the cute puppy, or do you want to research breeders, bloodlines, health certifications like OFA, CERT, and make sure that the litter you have selected from will yield the best possible conformation and health, and then pick the cutest one to your eyes?

Sorry, I do not see any education in this post.
I hope PS could (yet )save balance of opinions

Cut is not so simple like AGS shows it, David point is valid and very important for PS( I think)

I do not say what David is right or wrong. I say what Alternative David opinion, GIA opinion are very important for PS and consumer education( remember what ASG did not publish any observation tests( scientific based tests) untill now!! Please think why ASG did not do it until now)

Nobody yet can proof what cut is best, even what cut is better.

One cut can not be best for All. Ideal cut is absent

Please do not convert PS( consumer education forum) to AGS Fun club

I am not pro AGS and con GIA or via versa

I just want understand how we can grade cuts, how could we create cuts better then RBC H&A. I am doing R&D in this field more then 10 years.
then more I learn then more I am understanding how many I do not know in diamond cut grading.
If you want better understand cut, you need stop fighting, open mind, discuss and do TESTS

A lot of professionals who do not use ASG could give great input in improving cuts, RBC, and cut grading systems
Please respect knowledge and experience from "old " cutters. H&A did not come from ASG, it came from "old " cutters
"Tolkowsky " did not come from AGS or even from Tolkowsky. It came from "old" cutters.
all best cuts came from cutters and trade( not from Labs)
From historical point of view , new nice cut will not come from Labs
please give rights to 'alternative viewpoints'.

If David win competition ( or we receive 50-50) a lot consumers will receive new opportunities
If David lose competition a lot PS pro ASG consumers and vendors will very happy
In any case consumer education forum will win much more from nice discussions and honest competition than from fighting with 'alternative viewpoints'.

David,
if you will find your best 60/60 Horse please send me confirmation by OctoNus support system or to Garry.

I am not spend many time in PS now, PS has less and less 'alternative viewpoints' and become very boring for me
Early we had a lot of nice discussions what create a new knowledge for me at least. Now PS is not more source of new ideas for me.
I hope we can change it and you can give real input . Please find your sample

I am guaranty what we will give Full information how we did tests
I will very happy if you do not lose at least .
Sorry you have few chances to win, H&A AGS0 is real nice diamonds
I spend a lot of time, money and did not win yet. But I will try again and again.
I respect any other attempts do same. It is real challenge to beat AGS0 H&A

 

[strmrdr]

Date: 2/20/2009 4:19:51 PM
Author: Rockdiamond

Date: 2/20/2009 3:58:08 PM

Author: purrfectpear



Correct me if I''m wrong,

Purrfect, not that I believe you actually want me to correct you but yes, you''re wrong.

All due respect, but please don''t try to state my position.

You really do a poor job of it.



An idea that existed before Pricescope is not necessarily wrong Purrfect.

David the problem is you show no proof.
You do not have the creds here to say because I say so.
In fact no one has that totaly with me, I always say prove it then verify it for myself. Then when I find them right they earn respect.
Trying to keep up with Garry and Serg is why I know so much about diamond diamond cut. With a shout out to John and Jon for a ton of help along the way as well as others like Dave and Rich.

If you want to go around in thread after thread saying 60/60 is kewl because I say so you are going to get a ton of backlash not only from me but from the entire that''s nice now prove it crowd.
In that crowd is pretty much all the prosumers and a large chunk of the experts.
We have seen it time after time someone comes along running their fingers but can not back it up.
We are not interested in hearing it, show proof.

 

[glitterata]

I agree with Serg.

David says some 60/60 diamonds are at least as beautiful as AGS 0 H&As. I would love to hear more about these beautiful diamonds, what makes them beautiful, how they look different from H&As, how they''re similar, etc etc etc. Wouldn''t it be nice if consumers had even more kinds of beautiful diamonds to choose from?

I''m less interested in the argument about whether some GIA EX cuts are less beautiful than others. In that part of the thread, it seems as if David is saying all GIA EX cuts are necessarily beautiful, and other posters are saying that some of them--steep deeps, in particular--aren''t as beautiful as others. That argument seems less productive. David isn''t going to convince steep-deep haters that steep-deeps are beautiful just because GIA calls them excellent, and the anti-steep-deep camp isn''t going to change his mind.

On the whole, this thread has been much less uncivil than others I''ve read recently, which is great. I would love to see knowledgeable posters follow Serg''s lead and explore the potential of 60/60s.

 

[Garry H (Cut Nut)]

Date: 2/20/2009 2:45:24 PM
Author: Serg

Date: 2/19/2009 10:26:29 PM
Author: Garry H (Cut Nut)


i do not think you can have a H&A''s pattern in any 60:60 combination.

re

i do not think you can have a H&A''s pattern in any 60:60 combination.

Garry,


Why? What is about P41.75Cr34.5T60GirdleValley1.5%
Did I miss anything in definition H&A( I hope we are speaking about generic H&A ) or in definition 60/60

Sergey that stone does not have arrows and is a lot deeper than 60% - 61.6% - the girdle must be negative to achieve 60%

 

[strmrdr]

Date: 2/20/2009 5:32:19 PM
Author: glitterata
I would love to see knowledgeable posters follow Serg's lead and explore the potential of 60/60s.

If David ever comes up with some real information I might just do that.
Until then I would rather spend my time on the cuts I love and other things I think would be more useful.
Old cuts, step cuts and new designs, virtual facets, patterns and education are all better ways to spend my time than starting from scratch looking into 60/60s.
In those areas I can add to PS and in some cases add to the world of diamonds.
The marketplace has already settled the 60/60 vs near-tolk debate and it isn't going back anytime soon.

 

[Maisie]

I wonder how many people are now sitting questioning their GIA Ex cut grade diamonds. My previous stone was GIA Ex but it wasn''t 60/60. It was a stunning diamond with no black ring of death or whatever it was called. I remember when I was buying it I read that not all GIA Ex diamonds are that great. I was a bit wary that it would be awful but it wasn''t.

I just wanted to say that maybe not all GIA Ex are second rate.

And yes, all of the previous conversation in this thread went ''whoosh'' over my head.

In fact, I wonder why I even bothered posting this. Its probably nothing to do with what you were discussing!

 

[strmrdr]

Date: 2/20/2009 5:51:23 PM
Author: Maisie
I wonder how many people are now sitting questioning their GIA Ex cut grade diamonds. My previous stone was GIA Ex but it wasn't 60/60. It was a stunning diamond with no black ring of death or whatever it was called. I remember when I was buying it I read that not all GIA Ex diamonds are that great. I was a bit wary that it would be awful but it wasn't.


I just wanted to say that maybe not all GIA Ex are second rate.


And yes, all of the previous conversation in this thread went 'whoosh' over my head.


In fact, I wonder why I even bothered posting this. Its probably nothing to do with what you were discussing!

Hi Maisie,
You raise a good point.

There are some exceptional well cut GIA EX diamonds out there.
I would even go as far as the average GIA EX diamond in well cut.
But that average is slowly shifting as more cutters cut to the steep/deep side of GIA EX.
You could walk in a jewelery store and see not one less than optimal GIA EX if the stores buyer filters them out.
You could walk into another store and find a bunch because the stores buyer buys them for less and sells them at the same price as the other stores better cut diamonds.
It is that variability rather than any specific diamond that is the problem with GIA EX.

 

[glitterata]

Date: 2/20/2009 5:51:23 PM
Author: Maisie
I wonder how many people are now sitting questioning their GIA Ex cut grade diamonds. My previous stone was GIA Ex but it wasn''t 60/60. It was a stunning diamond with no black ring of death or whatever it was called. I remember when I was buying it I read that not all GIA Ex diamonds are that great. I was a bit wary that it would be awful but it wasn''t.


I just wanted to say that maybe not all GIA Ex are second rate.


And yes, all of the previous conversation in this thread went ''whoosh'' over my head.


In fact, I wonder why I even bothered posting this. Its probably nothing to do with what you were discussing!

Maisie, nobody said all GIA EXes are second rate!!! They just said some are better than others.

Imagine there''s a lab that certifies men''s height. This lab gives men a grade of "tall" if they''re over 5 feet 8 inches. Now, to me, a 5''8" man is not tall. So that lab''s "tall" grade includes some medium-height (or some would say short) men; getting the "tall" grade from the lab doesn''t actually guarantee that you ARE tall. But the "tall" grade also includes lots of genuinely tall men, since all the six-footers and up, men I consider tall, are also in the lab''s "tall" category.

Does that make it any clearer?

 

[Maisie]

I think its the title of this thread that might be misleading. Saying ''Can we trust GIA Ex cut grade'' implies that all ex grades are 60/60 which obviously they aren''t. Someone seeing this thread but not reading it might think they should avoid all GIA Ex.

 

[glitterata]

Date: 2/20/2009 5:45:56 PM
Author: strmrdr

Date: 2/20/2009 5:32:19 PM

Author: glitterata

I would love to see knowledgeable posters follow Serg''s lead and explore the potential of 60/60s.

If David ever comes up with some real information I might just do that.

Until then I would rather spend my time on the cuts I love and other things I think would be more useful.

Old cuts, step cuts and new designs, virtual facets, patterns and education are all better ways to spend my time than starting from scratch looking into 60/60s.

In those areas I can add to PS and in some cases add to the world of diamonds.

The marketplace has already settled the 60/60 vs near-tolk debate and it isn''t going back anytime soon.

Karl, you and I were posting at the same time; I certainly wasn''t disagreeing with you.

When I said I hoped knowledgeable people would explore the potential of 60/60s, I mostly meant that I hoped David would devote his energy here to the positive side of this conversation, and provide other experts with the means to explore the stones he says he finds beautiful.

As for the marketplace settling the debate, I know what you mean--but I also know that the marketplace has "settled" the question of OECs and other old cuts in favor of modern brilliants. However, I myself prefer the old cuts. So we don''t all always agree with the marketplace.

 

[John P]

Date: 2/20/2009 5:51:23 PM
Author: Maisie

I just wanted to say that maybe not all GIA Ex are second rate.

The fact that anyone could infer that shows how "in the ditch" this thread has gone.

Maise, I've seen thousands of GIA graded diamonds and only several EX with notable reductions in brilliance. All of those were in the steep/deep area being discussed. My concern is that such an area exists in EX at all.

Date: 2/20/2009 3:12:15 PM
Author: Rockdiamond

Garry , you, and others choose not to trust GIA..

Statements like that, which I normally would not reply to, may be what's throwing Maise off.

You know David, the people there are friends and colleagues; Al Gilbertson foremost among them (Gilbertson-scope was the basis for ASET by the way - did you know that?). I've always celebrated their introduction of a cut grading system in the big picture. My personal standards would call for some refinement, an opinion shared by others away from PS and here. I'm not saying anything that I haven't discussed with researchers at the lab. We've discussed much more in fact.

This thread began with a question. While I respect anyone's right to taste, I see identifying brilliant diamonds with reduced brilliance as a matter of consumer protection, and that is in large part my answer.

I may depart from you on that point and that's cool. As for "trust," I haven't found any grading system I agree with absolutely or trust implicitly. There are, however, people I trust.

 

[strmrdr]

If I hated GIA would I have bought this diamond for the love of my life?
It came with a lot of information above and beyond that GIA report but I would have wanted that information with an AGS report also.

 

[Rockdiamond]

Thank you so much Serg, and glitterata
The fact is, it might prove very difficult to even find such a stone today- but we do have, thankfully, a lot of cutter friends who would be more than happy to lend me a diamond for this test.
I''ll be more than happy to photograph it myself- or bring it to someone here in town to do ASET and IS photos ( or maybe learn how to take them myself, now that''s a scary thought).

Karl- you bring up a great point. What''s the proof that a well cut 60/60 is as well cut as a Near Tolk diamond?
Part of my point, is that proof, as it is, is totally subjective anyway.
I really have never seen a diamond GIA EX cut grade that has a detrimental ( to my eye) ring in the table.
I''m not saying such a stone does not exist, but I have not seen any examples.
If I can find an example of a GIA SEX cut grade steep deep and it looks bad to me, I will say so.
No question I am strong minded at times- but I am willing to learn.

All due respect to computer modeling of diamonds- heck, I want to cut your "Super Asscher"( sorry I don;t remember your official name for it- but it looks amazing)- but using a CG model to demonstrate a problem in the cutting of a diamond is an academic exercise.
I could make the case that it does not "prove" anything about a real diamond, and how it looks in person.

Do I love every GIA EX cut grade diamond, in terms of it''s cut? No.
That''s not what I''m saying.
For sure there are "mavens" on make.
People who really can notice the difference between a 57% and a 60% table.
For that group, it''s clearly beneficial to seek a diamond within the GIA EX cut grade ( or AGSL 0) that suits their taste.
ASET IS all that stuff is great for "proving" a diamond is a near Tolk.
But there''s also a lot of folks that choose by eye- and pick other combinations than would be approved of by a lot of people here on PS.
That''s why it is just giving other sides of the coin to discuss looking t diamonds without ASET or IS images.

It''s true that the diamonds we generally deal in on a daily basis- primarily fancy colors- could never be judged using ASET and IS.
But the same principles apply, from my perspective.
Look at the diamond. No matter what the ASET, IS and HCA say, it is the eye that''s going to be the final arbiter.
Taking into account the valid point that these tools are only being used for weeding out the bad stones, I still feel that it''s more important to look at actual photos, and video if possible.
We also have to remember that the selection tools admittedly weed out some very nice stones.

 

[Rockdiamond]

John, you have my apologies if I mis-categorized your feelings about GIA. If your position is that GIA''s cut grade includes "badly cut" diamonds- that is to say, not diamonds you don''t prefer, but badly cut diamonds, then it would seem you don''t go along with GIA and the parameters of their cut grade.
Brian wrote a great article explaining that viewpoint but it really does imply GIA is doing something wrong, rather than taking a broader view of cut.
Maybe "trust" was a poor choice of words, but in all fairness, I felt just a little blindsided being attacked for failing a test without the benefit of knowing what it was I was being tested for.

I do believe we agree on most things.
And I really respect your knowledge, and ability to share it.

I have seen a lot of consumers being told to watch out for "Steep Deep"- in GIA EX cut grade.
If you''ve seen theses stones, and believe they are truly bad news, of course it would be correct to advise people that they should watch out for them.
I have not seen one- nor ever heard anyone use the term "Steep Deep" outside PS.
Karl- here in NY, there''s no "steep deep" discount that I''ve ever heard of. A GIA EX cut grade goes for what it goes for. Maybe others have different experiences....

 

[Serg]

Date: 2/20/2009 5:42:23 PM
Author: Garry H (Cut Nut)

Date: 2/20/2009 2:45:24 PM
Author: Serg

Date: 2/19/2009 10:26:29 PM
Author: Garry H (Cut Nut)


i do not think you can have a H&A''s pattern in any 60:60 combination.

re

i do not think you can have a H&A''s pattern in any 60:60 combination.

Garry,



Why? What is about P41.75Cr34.5T60GirdleValley1.5%
Did I miss anything in definition H&A( I hope we are speaking about generic H&A ) or in definition 60/60

Sergey that stone does not have arrows and is a lot deeper than 60% - 61.6% - the girdle must be negative to achieve 60%

Garry,
Sorry for missprint, should be P40.75Cr34.5T60GirdleValley1.5%

 

[Serg]

60/60

 

[Serg]

ASG0, Same Pavilion, crown angles , Only table is different

T=58, Total depth 60.7

There is important difference from 60/60???

 

[Rockdiamond]

Will this stone work?
I would not call this the "best" in 60/60- but it does have a nice spread, and a lot of brilliance.
Here''s the stats:
2.04ct
H/SI1
8.17-8.22 X 4.96
d=60.4
T=60
girdle- med-sthk
Pol=EX
Sym=EX
Cut Grade=EX
Crown Height 14%
Crown Angle: 35.5degree
Pavilion Depth: 42%
Pavilion angle- 40.8
lgf=75%
star=50%
culet=none


AS I mentioned, the diamond is very nice, but I''m not falling off my chair.
Plus it''s a weak SI1....
Should we use this one?

 

[stone-cold11]

David, that is not in the steep deep region. HCA scored a 3.2 so will not really proof your point of GIA Ex with steep deep proportion is still good looking.

 

[Rockdiamond]

This was the 60/60 part of the conversation, not the steep deep part.

 

[strmrdr]

Date: 2/24/2009 7:20:01 PM
Author: Rockdiamond
Will this stone work?

I would not call this the ''best'' in 60/60- but it does have a nice spread, and a lot of brilliance.

Here''s the stats:

2.04ct

H/SI1

8.17-8.22 X 4.96

d=60.4

T=60

girdle- med-sthk

Pol=EX

Sym=EX

Cut Grade=EX

Crown Height 14%

Crown Angle: 35.5degree

Pavilion Depth: 42%

Pavilion angle- 40.8

lgf=75%

star=50%

culet=none



AS I mentioned, the diamond is very nice, but I''m not falling off my chair.

Plus it''s a weak SI1....

Should we use this one?

AGS gives those basic numbers the potential to score 2.
Looking at the IS for the basic parameters it actually agrees with your assessment nice but not the best.
It would make a nice center slot holder in a 3 diamond comparison.
One you find hot and one you don''t.
For the one you don''t I would look for one with a pavilion angle around 41.4 and a crown angle of 34ish.
That should be one you don''t like as much as the one you have now.

I don''t know what the numbers are on the HW you used to work with so cant help you there.
I can give you some numbers to look for of one that is predicted to be better performing than the one you have now if you want them.

 

[Rockdiamond]

That would be great Karl!

In 1976-''79, when I worked at Winston, cutting was done without computers, and we never dealt with more than basic measurements.
As time went on, I saw other styles of cutting- like when Lazaare Kaplan started cutting "Ideal" diamonds.
When I saw the LK stones, I immediately felt the tables looked small. The Winson Make was "spreadier". Not to take away from the Near Tolks- I was also really impressed with the precision of the Kaplan stones.

I can''t say for sure that HW was cutting every stone to a 60% table- but as GIA reports became more common, and I could recognize the makes I was taught on. I''ll call some of my old classmates from those days and ask.....
The entire point of the thread was that slightly spreadier diamonds, such as 60 depth, and table, were thought to be the nicest makes in the ''60''s''70''s and ''80''s. And the aesthetic reasons those numbers were chosen are no less valid today.

Of course today, the market has turned around due to a lot of factors. Near Tolk is the king of the market in "Fine Make" diamonds.
But I still feel that in many ways a spreadier stone possess the more modern design, if compared to a Near Tolk, and the subtle differences between the two are totally subjective.
Of the viewers that could see the difference, my feeling is that they''d be evenly divided, if comparing a knockout 60./60 to a knockout Near Tolk.
I appreciate the chance to discuss this, as PS is one of the most detail oriented conversations about diamonds you can find anywhere.


Anyway, I''ll see if I can find another stone I like more.

For comparison, I also got a second stone that''s a triple EX GIA, a very nice stone for sure, but also not the best, IMO.
2.09ct
H/VS2
8.19-8.26 X 5.06
d=61.5
T=55
girdle- med-(faceted) 3.5%
Pol=EX
Sym=EX
Cut Grade=EX
Crown Height 15.5%
Crown Angle: 34.5degree
Pavilion Depth: 42%
Pavilion angle- 40.6
lgf=75%
star=50%
culet=none


By the way, It seems that I am going to have to admit that these two stones have certainly made me re-think my EX GIA cut grade for rounds stance.
I stand corrected.
If you''re a person really wanting specific things in the cut of a diamond, you''re going to need more than just the GIA EX cut grade.
Not to say that either if these stones is not truly lovely.
Either would satisfy many recipients. Both can be called really well cut- but neither is "connoisseur cut"


These are both really nice- but if I was shopping for either near tolk, or 60/60, I''d keep looking.....