Discuss Review of GIA Foundation article posted in the Journal

[JohnQuixote]

Date: 1/12/2005 6:34:21 AM
Author: Garry H (Cut Nut)

Rhino overstates them as part of a belief or a commercial strategy - I see less than 5% of otherwise nice stones with small minor facet irritations - and almost never really bad e.g.'s

Garry, I think the “commercial strategy” statement is unfair to Rhino. Truthfully it would be a lot easier for him to do away with the time-consuming efforts and sell low-standard, phony H&A stones using minimal imagery and limited consumer education. His in-depth analysis is motivated by the same passion for understanding diamond beauty as yours or ours is. I applaud him for contributing to the overall knowledge base here. Brian Gavin and Paul Slegers are both in the business of working to understand and evolve diamond beauty. Neither of them “overstates” what they observe for commercial strategy and I don’t believe Rhino does either.

Thus, I believe “overstates” is to Rhinoceros as “conjecture” is to Oz-man.
The Knight counter-conjectures that Oz-man “overstates” the following...

Author: Garry H (Cut Nut)

I have no beef with the anal approach of Brian and Rhino et al; but they are working in a very rarified area of diamond cut and it is not GIA's or my intent that this be a standard expectation. Even Peter Yantzer from AGS, who might like to buy a super ideal cut for himself because he can truly appreciate the skill and precision that goes into making such a product - does not seek to set such standards for normal commercial grading by providing extra recognition for H&A"s pattern grades. If you ask him why, he say's that there is insufficient evidence to show that a diamond with very nice symmetry is less beautiful than one with perfect symmetry.>>

First, I understand the decision not to provide extra recognition for H&A patterning in normal commercial grading. The market is, as you say, rarified. You constantly rattle this saber (I’m not sure why, since most of us steeped in the particulars of this niche market promote it realistically).

I am curious about the symmetry statement above. If this is the case then why do they even grade symmetry on an AGS report? They should drop it if there is sufficient evidence that it’s an oxymoron... Or did I misunderstand? When you refer to Peter Yantzer’s symmetry comment do you mean what AGS is grading – which is meet point symmetry - or is he referring to patterning/physical Hearts & Arrows symmetry? Though they are not the same thing they are interdependent: Bad lab graded (meet point) symmetry can exist due to facet yaw, and this will be reflected in the patterning.

 

[strmrdr]

hmmm if your going with a "hca/gia/ags ideal" round which has nothing but bright return going for it unless its h&a why not just buy a mirror?

/me grumbles rounds smounds and goes back to designing the strmrdr S.E. cut standard.
Hmmmm I should apply for a gov. grant for that one.

 

[Garry H (Cut Nut)]

John with regard to my idea of levels of symmetry grade, there rae 2 puposes.

1. to show very high level''s of craftsmanship. This is nice to have, but is not the over riding issue in my opinion - but people like Brian and Paul count it as the bees knees
2. to indicate the effects on the quality of a diamonds appearance to an observer.

My opinion is #2 is being ignored by current grading systems as reported in Grading the Symmetry of Round brilliant cut Diamonds by Yuri, Sergey and moi. The AGS do a better job than most of getting the optical symmetry right. GIA seem to have ignored it in their current article and seem to think that optical symmetry is for purists. But I would have thought that I was well enough known in the Gemological world as not being an optical symmetry purist. So their lumping the Ideal-scope (page 202) as a "device for viewing specific patterns or pattern elements in diamonds" is rather odd. It seems at no stage either did they discriminate between leakage and obstruction in a clear and simple manner in their study. Just darkenss and brightness etc.
anyway back to the topic as I am wandering.
It seems GIA will not want to shake the boat of traditional facet meet pointing and the symmetry grade report spat out from a Sarin type scan 9with all it''s stoopid "the table as the centre of the earth" philiosophy. AGS on the othe hand have embrassed colored reflected imagery and will be probably putting Al Gilbertson type (Al is one of the GIA authors and staudy team) multi coloerd Ideal-scope type images onto the diamond grading report (how odd is that given Al has a patent on the idea that he would presumably be excercising for a royalty fee).

Does that answer the question John?

Oh and BTW - remeber i think symmetry is more important when the diamond is cut near the edge of a excellent cut (say C35 P41) and less of a problem if the stone is in a "sweet spot" (say C34.5 P40.5)

 

[Garry H (Cut Nut)]

I just read the GIA Loupe magazine and I quote:

"Each of the new Reports will contain an overall cut grade, expanded proportion information in the form of a new graphic and a brief explanation of the Four Cs."

That IS a step forward.

I wonder if they will be also listing the upper and lower girdle facet info too?

 

[strmrdr]

Date: 1/13/2005 10:59:24 PM
Author: Garry H (Cut Nut)
I just read the GIA Loupe magazine and I quote:



''Each of the new Reports will contain an overall cut grade, expanded proportion information in the form of a new graphic and a brief explanation of the Four Cs.''

That IS a step forward.

I wonder if they will be also listing the upper and lower girdle facet info too?

Kewl
That is a step forward if its what they are going to do.

 

[valeria101]

Date: 1/13/2005 1:204 PM
Author: JohnQuixote

Date: 1/12/2005 72:22 AM
Author: valeria101

is it possible to improve the looks of a stone with so-so crown&pavilion match by modifying the minors ?

Ana, I was intrigued by this as well. DiamCalc, yes?

Well, I have got an e-mail from Jonathan saying that he things this might work as well. There''s a promise for more detail as well. It would be nice to hear about these and anything nice and not harts and arrows, of course.

Here''s Jonathan''s message:

"The minor facets DO impact the optical properties of a diamond. In some cases the differences can be negligible and in others obvious. Point being… they can’t be ignored since they constitute 2/3’s of the reflective portions on and in the diamond. One of the greatest impacts regards a very key optical property … namely scintillation (or the sparkle factor!) which is determined by the strength or quality of light being reflected through the crown. In this case more blacks and dark reds are imperative."

I know he is updating the GOG website and what not, just hope there''s more to come from the source

 

[Garry H (Cut Nut)]

The use of the 2/3rds factor is completely erroneous and irrelevant.
The minor facets are tied to the major facets, not the other way around.

You can increase or decrease the upper girdle facets by around one and a half degrees. The effect is to decrease light return and increase contrast OR the other way around. The point is there is not often a benefit for the cutter in producing diamonds with lousy minor facet proportions because there is no effective change in weight. -so it is not like there are 90% of stones with bad minor facet combinations. But there are 90% of diamonds with bad major facet proportions.

If a diamonds major porprotions are bad, no amount of minor facet tinkering will save the stone.
If the major facet proportions are great - it is very hard to find examples of deleterious minor facets.

The issue is not are they important. In my mind it is a scale of importance. I would like to help improve diamond cut quality. The problem is a major one, not a minor one

.

Finally HCA is a tool for rejecting known bad performers. It does this pretty well. But I always ask next for an ideal-scope image / opinion. If you already have the Ideal-scope then you do not need the HCA.
The ideal-scope shows minor facet deficiencies.

 

[valeria101]

Date: 1/14/2005 90:56 PM
Author: Garry H (Cut Nut)

If a diamonds major porprotions are bad, no amount of minor facet tinkering will save the stone.
If the major facet proportions are great - it is very hard to find examples of deleterious minor facets.

So... there's some ballast in the GIA cut grading: not much use added, just "value" as it's called if I'm not mistaking

[edited to explain] Since the information about minor facets is not crucial for judging 99% of diamonds - as you say Garry - then it is redundant on the report.

Perhaps the lab felt this is a way to promote their grades as "different" and "better" (so they added value to their paper), but the more complex metrics make reading the grades more difficult in all cases and more useful in just few cases (those with deleterious minor facets, as you call them). So, that's just ballast - useless cargo meant to weigh down the grades' authority.

 

[strmrdr]

hmmm If the cut grades actually improve the standards of what is an acceptable cut and more diamonds are cut to "sweet spots" then the 1% where minor facets play a bigger role would increase in number, currect?

Therefore the arguement that its important only to a small percentage of diamonds over time will go away.

Lets face it anything that GIA comes up with we will be stuck with for a long time.
Therefore they owe it to the consumers to get it right the first time.

 

[Regular Guy]

"I just read the GIA Loupe magazine and I quote:

"Each of the new Reports will contain an overall cut grade, expanded proportion information in the form of a new graphic and a brief explanation of the Four Cs."
That IS a step forward."

---------------

Will training for gemologists turning into appraisers be affected by these changes?

 

[valeria101]

Date: 1/15/2005 11:20:38 AM
Author: Regular Guy

''Each of the new Reports will contain an overall cut grade, expanded proportion information in the form of a new graphic and a brief explanation of the Four Cs.''
That IS a step forward.''

Yes, sure... I was just wondering how much they turned sideways before taking that step forward !

 

[Garry H (Cut Nut)]

Well it is great that we only have minor issues to argue about

I have no doubt that cutters are not silly when it comes to minor facets.
But thre iis a huge opportunity to improve diamond cutting when as Storm says - there are more diamonds cut with better major proportions.
But one problem with the GIA approach is that very small changes in major proportion relationships can result in alternative ideal proportions in minor facet proportions.

1. GIA are reporting the minor facets in plus minus 5% ranges. Sorry guys - but that is plain dopey.
2. Upper (and lower) girdle indexing (painting and digging) causes more impact than UG length.

Can you see why I never bothered to do it?

OctoNus on the other hand gives manufacturers tools they can use to plan for the optimum relationships that only computers can resolve.
And 3D modelling can give labs the tools to grade the cut quality.

But this ham fisted GIA approach will not really achieve much from what i can understand

 

[valeria101]

Date: 1/15/2005 6:21:34 PM
Author: Garry H (Cut Nut)

Well it is great that we only have minor issues to argue about

At least those college debates ended with bear rounds

 

[JohnQuixote]

Date: 1/13/2005 7:33

1 PM
Author: Garry H (Cut Nut)
John with regard to my idea of levels of symmetry grade, there rae 2 puposes.

1. to show very high level's of craftsmanship. This is nice to have, but is not the over riding issue in my opinion - but people like Brian and Paul count it as the bees knees

2. to indicate the effects on the quality of a diamonds appearance to an observer.

My opinion is #2 is being ignored by current grading systems as reported in Grading the Symmetry of Round brilliant cut Diamonds by Yuri, Sergey and moi. The AGS do a better job than most of getting the optical symmetry right. GIA seem to have ignored it in their current article and seem to think that optical symmetry is for purists. But I would have thought that I was well enough known in the Gemological world as not being an optical symmetry purist. So their lumping the Ideal-scope (page 202) as a 'device for viewing specific patterns or pattern elements in diamonds' is rather odd. It seems at no stage either did they discriminate between leakage and obstruction in a clear and simple manner in their study. Just darkenss and brightness etc.

anyway back to the topic as I am wandering.

It seems GIA will not want to shake the boat of traditional facet meet pointing and the symmetry grade report spat out from a Sarin type scan 9with all it's stoopid 'the table as the centre of the earth' philiosophy. AGS on the othe hand have embrassed colored reflected imagery and will be probably putting Al Gilbertson type (Al is one of the GIA authors and staudy team) multi coloerd Ideal-scope type images onto the diamond grading report (how odd is that given Al has a patent on the idea that he would presumably be excercising for a royalty fee).

Does that answer the question John?

Garry, that mostly answers the question - though I confess to being perplexed by the answer (on GIA’s part, not yours)

With regard to 1. Righto. I agree that for purposes of normal commercial grading it is not necessary to serve the boutique world of Brian and Paul exclusively.

With regard to 2. I am at a loss to understand why GIA treated IdealScope as a patterning/symmetry viewer (am I reading that correctly) (?). If you need a letter of verification stating that you are not an OS purist I’ll gladly write it

.

Quickly on AGS – any insight on why Gilbertson?

How about this perspective on the meet point make versus physical symmetry and patterning… For Brian and Paul’s part, as craftsmen, I’m sure you understand the desire to have recognition for precision patterning where it exists - even if it were separate from the grade assigned to overall cut. I think it’s realistic to expect that some day in the future. After all, the GIA’s been around for over 70 years, but is only now able (and willing) to include proportion measurements on the report. Recognition and understanding of precision patterning is still in relative infancy.

I’ve often thought a patterning grade could exist as an eventual sub-category within top grades of cut…Maybe graded upon request by vendor or consumer. That way the degree of patterning trueness (H&A by any other name) would have the possibility of existing on the report.

Oh and BTW - remeber i think symmetry is more important when the diamond is cut near the edge of a excellent cut (say C35 P41) and less of a problem if the stone is in a 'sweet spot' (say C34.5 P40.5)

Logical, which is why I believe my idea has merit…In this manner the choice could be made with individual stones to have patterning graded and included on the report in a way which would not necessarily impact the overall cut grade, but could be viewed as a bonus to the cut.

 

[JohnQuixote]

Date: 1/15/2005 6:21:34 PM
Author: Garry H (Cut Nut)
1. GIA are reporting the minor facets in plus minus 5% ranges. Sorry guys - but that is plain dopey.

Is this why on this page of your review star and lower girdles for RD01, RD08 and RD20 are specified with two numbers - the actual in parenthesis I assume? I am very disappointed by this... Fuel for the fire of "politics" with regard to inclusion of the minors if they're just going to throw a dart at those measurements. Why even bother?

Question...why is RD01 lgf cited as 75% when the parenthetical says 81%? Typo?

And 3D modelling can give labs the tools to grade the cut quality.

But this ham fisted GIA approach will not really achieve much from what i can understand

Looks like the AGS delay was wise. Garry, do you golf? Are you familiar with the term "going to school?"
Yantzer is closest to the pin.

 

[JohnQuixote]

Date: 1/15/2005 7:56:44 AM
Author: strmrdr
hmmm If the cut grades actually improve the standards of what is an acceptable cut and more diamonds are cut to 'sweet spots' then the 1% where minor facets play a bigger role would increase in number, currect?

Good point Strm.
But it's loopy to include them in 5% increments.

[Just for an acceptability comparison, that's a full half of the range of error for BScope, which is oft-condemned as preposterous]

 

[Garry H (Cut Nut)]

Date: 1/17/2005 12:40:50 PM
Author: JohnQuixote

Quickly on AGS – any insight on why Gilbertson? Al Gilbertson has a Patent on multi colred reflection instruments (which is interesting for me because many years ago I started putting a fluoro green reflector into my Firescope to show students in my GAA diamond classes how they could tell where light was coming from - same same)

Recognition and understanding of precision patterning is still in relative infancy.



Logical, which is why I believe my idea has merit…In this manner the choice could be made with individual stones to have patterning graded and included on the report in a way which would not necessarily impact the overall cut grade, but could be viewed as a bonus to the cut.
Labs do not need to do this because it is so easy to demonstrate with a photo. In tis respect I think IGI has the answer - put a photo on the report. When AGS release their new reports - you will have it

 

[Garry H (Cut Nut)]

Date: 1/17/2005 1

0:21 PM
Author: JohnQuixote

Date: 1/15/2005 6:21:34 PM
Author: Garry H (Cut Nut)
1. GIA are reporting the minor facets in plus minus 5% ranges. Sorry guys - but that is plain dopey.

Is this why on this page of your review star and lower girdles for RD01, RD08 and RD20 are specified with two numbers - the actual in parenthesis I assume? I am very disappointed by this... Fuel for the fire of 'politics' with regard to inclusion of the minors if they're just going to throw a dart at those measurements. Why even bother?

Question...why is RD01 lgf cited as 75% when the parenthetical says 81%? Typo?
Some of the same stones were listed in both the Fire article from Fall 2001 and this article from Fall 2004. The earlier listings show no sign of an attempt to round the #'s. The latter #'s are all rounded off. I posted the earlier #'s in brackets when they were different to the later ones.

There is a comment somewhere indicating that some of the stones may have been recut - but for the most part this could not have been true as the stones sometimes got deeper in the new data.



Looks like the AGS delay was wise. Garry, do you golf? Are you familiar with the term 'going to school?'
Yantzer is closest to the pin. No - Hate Golf John (= i am lousy at it

)

 

[Garry H (Cut Nut)]

Date: 1/17/2005 1:13:11 PM
Author: JohnQuixote

Date: 1/15/2005 7:56:44 AM
Author: strmrdr
hmmm If the cut grades actually improve the standards of what is an acceptable cut and more diamonds are cut to ''sweet spots'' then the 1% where minor facets play a bigger role would increase in number, currect?

Good point Strm.
But it''s loopy to include them in 5% increments.

[Just for an acceptability comparison, that''s a full half of the range of error for BScope, which is oft-condemned as preposterous]

Lower and upper girdle facets have small ranges - maybe 75% to 90% and 40 to 60%, so plus minus 5% means we only have 3 or 4 possabilities - this is one way GIA have simplified and made a problem more manageable - the same problem that stopped me from including lower girdle facets in hCA.

 

[JohnQuixote]

Date: 1/17/2005 2:24:15 PM
Author: Garry H (Cut Nut)

JQ: Logical, which is why I believe my idea has merit…In this manner the choice could be made with individual stones to have patterning graded and included on the report in a way which would not necessarily impact the overall cut grade, but could be viewed as a bonus to the cut.

Labs do not need to do this because it is so easy to demonstrate with a photo. In tis respect I think IGI has the answer - put a photo on the report. When AGS release their new reports - you will have it

Will AGS be putting a pavilion patterning photo on their new reports? Or just the Gilbertson image?

 

[JohnQuixote]

Date: 1/17/2005 2:30:16 PM
Author: Garry H (Cut Nut)

JQ: Looks like the AGS delay was wise. Garry, do you golf? Are you familiar with the term 'going to school? Yantzer is closest to the pin.

No - Hate Golf John (= i am lousy at it

)

"Going to school" just means the guy who putts last (the one who's ball is closest to the pin) has the opportunity to watch the others and learn from their mistakes, or "read the line" of the ball. AGS' delayed release of their system may be akin to "going to school."

As for golf...I believe it should be given up at least twice per month.

 

[JohnQuixote]

Date: 1/17/2005 2:36:55 PM
Author: Garry H (Cut Nut)

Lower and upper girdle facets have small ranges - maybe 75% to 90% and 40 to 60%, so plus minus 5% means we only have 3 or 4 possabilities - this is one way GIA have simplified and made a problem more manageable - the same problem that stopped me from including lower girdle facets in hCA.

OK, I'll ultimately file this in the overall commercial grading drawer of "hair-splitting," but I wish they had not done this unless they intended to be more accurate with it.

I've attached lgf78% and lgf82%. You're telling me these would be gauged the same?? 80%?? Where's that mad smiley thing?...Oh here it is...

There are notable differences in the character these 2 diamonds will have given equal sets of proven major proportions.

I understand the global approach, but this does seem "ham-fisted." Promise moi HCA2.0 will be more precise?

 

[valeria101]

Date: 1/17/2005 4:17:43 PM
Author: JohnQuixote

I''ve attached lgf78% and lgf82% [...] There are notable differences in the character these 2 diamonds will have given equal sets of proven major proportions.

The photos are different allright - they show that by-the-book harts and arrows need more precission than that. But is the 5% still too approximative to guess overall light return (as it''s done for fancies) ?

How do these guys look face up ?

 

[JohnQuixote]

Date: 1/17/2005 4:41:51 PM
Author: valeria101

Date: 1/17/2005 4:17:43 PM

Author: JohnQuixote

I've attached lgf78% and lgf82% [...] There are notable differences in the character these 2 diamonds will have given equal sets of proven major proportions.

The photos are different allright - they show that by-the-book harts and arrows need more precission than that. But is the 5% still too approximative to guess overall light return (as it's done for fancies) ?

How do these guys look face up ?

Val, this is splitting hairs on well-cut diamonds. Overall light return will not be influenced enough to be noteworthy.

Garry: "If a diamonds major porprotions are bad, no amount of minor facet tinkering will save the stone.
If the major facet proportions are great - it is very hard to find examples of deleterious minor facets"

As for how they look face up - the 78% lgf will have a nice balance of WLR and DCLR, and better contrast in diffuse light. The 82% would score better on BScope or in direct lighting, but diamonds with such pronounced splits in the clefts of the hearts and notable separation of hearts from arrowheads have less contrast and consistency over a broad range of light conditions. It is a question of the character of the beauty, not the overall beauty.

NONE of the above considerations would influence the IdealScope footprint and NONE should qualify either for a better or worse grade from any lab.

I am being too nitpicky about this in the large scheme of this thread.

 

[Garry H (Cut Nut)]

Date: 1/17/2005 3:56:21 PM
Author: JohnQuixote

Date: 1/17/2005 2:24:15 PM
Author: Garry H (Cut Nut)

JQ: Logical, which is why I believe my idea has merit…In this manner the choice could be made with individual stones to have patterning graded and included on the report in a way which would not necessarily impact the overall cut grade, but could be viewed as a bonus to the cut.

Labs do not need to do this because it is so easy to demonstrate with a photo. In tis respect I think IGI has the answer - put a photo on the report. When AGS release their new reports - you will have it

Will AGS be putting a pavilion patterning photo on their new reports? Or just the Gilbertson image?

I think boys in the desert might not be as interested in bottoms as top''s. cetainly seems like the girls in Vegas dress for that effect!

 

[JohnQuixote]

Date: 1/17/2005 5:56:10 PM
Author: Garry H (Cut Nut)

JQ: "Will AGS be putting a pavilion patterning photo on their new reports? Or just the Gilbertson image?"

I think boys in the desert might not be as interested in bottoms as top's. cetainly seems like the girls in Vegas dress for that effect!

Take that tongue out of your cheek right now, young man!

Or...to continue in impish fashion...a wet T contest is a poor substitute for a pageant assessing bottom, top AND character.

 

[valeria101]

Date: 1/17/2005 5:17:14 PM
Author: JohnQuixote

Val, this is splitting hairs on well-cut diamonds. Overall light return will not be influenced enough to be noteworthy.

So... fast forward to new GIA paper. Do you think their top two grades (say) might come close to the cut quality thought by the WF Eexpert Selection ? (assuming my hunch is right that those stones are more or less H&A but selected for better than usual optics regardless).

 

[JohnQuixote]

Date: 1/17/2005 8:35:44 PM
Author: valeria101

So... fast forward to new GIA paper. Do you think their top two grades (say) might come close to the cut quality thought by the WF Eexpert Selection ? (assuming my hunch is right that those stones are more or less H&A but selected for better than usual optics regardless).

Ana, I cannot say for certain until we see GIA final polish.

As it stands now your hunch is right - Expert Selection RBs often are near-true H&A but never marketed as such (we only recognize ACA as true H&A). The majority of stocked ES are AGS0/AGS1. Any falling outside 1 are selected for outstanding optics... As you know, there are proportions outside given 'ideal' specs that can produce great visual results - but they are specific to particular combinations and hard to quantify in simple terms.

This is why it's difficult to quantify cut quality using proportions alone - and why HCA is a helpful tool, but direct assessment (like IdealScope) always trumps HCA.

 

[lostdog]

" Expert Selection RBs often are near-true H&A but never marketed as such (we only recognize ACA as true H&A"

Here's a related question. The Expert Selection AGS RB's have AGS Diamond Quality Reports while the A Cut Above's have the Diamond Quality Documents.

Would an ES stone sold as an "Ideal Cut" with a DQR likely get an AGS 000 if sent for a DQD instead?

(assuming those listed as "ideal/ideal" polish/symmetry on the WF site itself and as "excellent/excellent" polish/symmetry in the DQR, since that's the highest DQR p/s grade).

 

[JohnQuixote]

Hi LD,

First, a bit of trivia...The term "AGS 000" (as it would appear on a DQD) is commonly misconstrued. Triple 0 actually means a diamond with a cut grade of AGS Ideal 0 (including ideal polish, ideal sym and ideal proportions), a color grade of AGS 0 (D) and a clarity grade of AGS 0 (Flawless).

"Triple Ideal" is a more appropriate term for the cut grade of AGS Ideal 0, since it infers ideal sym, ideal polish and ideal proportions.

EDITED to reflect new AGS Position as of 2005: See this link for new AGS000 Definition

As to the meat of your question...A diamond with ex/ex in polish/sym, if sent in to AGS for a DQD rather than the DQR, might receive ideal rather than ex in one or both aspects. Relative to this thread, it's been noted that the difference between those grades will not have a visible difference to the naked eye.

I'll PM you regarding particulars of the ES stones you asked about.