A cut above vs regular cut

[John P]

David, I hesitate to wade into this pond as it won't change anything. But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

INDUSTRY
http://www.diamonds.net/Magazine/Article.aspx?ArticleID=45475&RDRIssueID=117
“AGS has succeeded in bringing science to the forefront of diamond design”

I respect the following:

You may not believe our world is usually lit from above - the scientific system does.
You may not believe people like to tilt diamonds back and forth - the scientific system does.
You may not believe 10 inches is a common viewing distance - the scientific system does.
You may not believe brightness is a performance priority - the scientific system does.
…Insert whatever else you think should be different or find “arbitrary.”

That’s all fine. Vive la difference. But your disagreement, or mine, doesn't invalidate the foundation, development, peer-review and published fact of this working metric, which is entirely based in repeatable science.

Fancy Shape Cut Grade from AGS
http://www.diamonds.net/News/NewsItem.aspx?ArticleID=11617
“This is the industry’s first scientific cut grade for the princess cut.”

Scientific Recognition for AGS Cut Grade
http://www.diamonds.net/news/NewsItem.aspx?ArticleID=19529
“Recognition and backing by the scientific community.”

Again, no problem to disagree. But I ask that we maintain respect for the hard work and achievements of our peers.

 

[Texas Leaguer]

David, I hesitate to wade into this pond as it won't change anything. But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

INDUSTRY
http://www.diamonds.net/Magazine/Article.aspx?ArticleID=45475&RDRIssueID=117
“AGS has succeeded in bringing science to the forefront of diamond design”

I respect the following:

You may not believe our world is usually lit from above - the scientific system does.
You may not believe people like to tilt diamonds back and forth - the scientific system does.
You may not believe 10 inches is a common viewing distance - the scientific system does.
You may not believe brightness is a performance priority - the scientific system does.
…Insert whatever else you think should be different or find “arbitrary.”

That’s all fine. Vive la difference. But your disagreement, or mine, doesn't invalidate the foundation, development, peer-review and published fact of this working metric, which is entirely based in repeatable science.

Fancy Shape Cut Grade from AGS
http://www.diamonds.net/News/NewsItem.aspx?ArticleID=11617
“This is the industry’s first scientific cut grade for the princess cut.”

Scientific Recognition for AGS Cut Grade
http://www.diamonds.net/news/NewsItem.aspx?ArticleID=19529
“Recognition and backing by the scientific community.”

Again, no problem to disagree. But I ask that we maintain respect for the hard work and achievements of our peers.

Nice, well rounded perspective John. It is important to remind folks of the history of the development and the commentary published by major sources regarding the ground breaking nature of what AGS has done in the field of cut quality analysis. It's not small stuff.

 

[pfunk]

I think it is quite safe to say the ray tracing approach is quite scientific. What is questionable is how the different grades equate to beauty. Obviously with the linear scale from 0-10, a consumer would assume a 0 is more beautiful than a 1, which is equally more beautiful than a 2, which is equally more beautiful than a 3, and so on and so on.

The grading looks at objective measures such as leakage, contrast, etc and penalizes according to the presence of "deficits". One would assume more of those AGS "deficits" would equate to a less beautiful diamond. Human perception would suggest otherwise, as certainly there are loads of people whose eyes would gravitate towards a diamond that is anything but "ideal" according to those who came up with the AGS system.

This is why, in my opinion, human observations should somehow be taken into account. It is fine to come up with a set of grades based off the science your instruments are capable of, but before implementing it you should be sure it agrees for the most part with humans perceptions. Duplicating the power and versatility of the human eye with science is an uphill battle. Trying to trick the eye into thinking something is more beautiful because it has a better cut grade will fail. The eye likes what it likes, no matter what any instrument might suggest.

The problem is, you can't show a consumer's eyes the various diamonds they are considering in every lighting environment they will encounter. Their preference between stones could change multiple times depending on where they are viewing them. Likewise, you can't grade a diamond in infinite lighting situations. At some point, you have to come up with a set standard for your grading. There will NEVER, however, be a standard for viewing environment. How can anyone possibly overcome the challenge of infinite viewing conditions AND replicate the power of the human eye with instruments? It is just not possible. I take my hat off to those who plug away at it though. And for what it is worth, I have seen videos of AGS 0, 1, and 2 princess cuts and my eyes did prefer 0 to 1 to 2 in those videos. Having said that, I do see where David is coming from when he criticizes the AGS 0-10 scale. Certainly it isn't perfect and not everyone will agree that it is in line with human perception of beauty. However, people are often led to believe that it is ironclad and that any stone that is AGS graded has a vastly superior chance to be beautiful.

 

[Rockdiamond]

HI John!
I'll answer some below in blue

David, I hesitate to wade into this pond as it won't change anything. But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

INDUSTRY
http://www.diamonds.net/Magazine/Article.aspx?ArticleID=45475&RDRIssueID=117
“AGS has succeeded in bringing science to the forefront of diamond design”

I respect the following:

You may not believe our world is usually lit from above - the scientific system does. First, scientific systems don't "believe" anything. Science involves fact, not beliefs, or in this case, commercial concerns. IN terms of the world being lit from above- I can think of few viewing environments where that statement is surely true. Standing outside at noon. I can think of many environments where light is coming from many directions. Right now I'm sitting in my office and there's more light coming in a 45 degrees than directly overhead. Many places people look at diamonds have main lighting sources that are not directly overhead.
You may not believe people like to tilt diamonds back and forth - the scientific system does. We agree that tilt is crucial to viewing a diamond. That's why a single static ASET may need to be interpreted differently than a simplistic "Red is better than Green"
You may not believe 10 inches is a common viewing distance - the scientific system does. I agree that's a common distance.
You may not believe brightness is a performance priority - the scientific system does. I agree that brightness is a priority- but perceived brightness is by no means consistent from one individual to the next- and again, lighting comes into play
…Insert whatever else you think should be different or find “arbitrary.”

That’s all fine. Vive la difference. But your disagreement, or mine, doesn't invalidate the foundation, development, peer-review and published fact of this working metric, which is entirely based in repeatable science.

Fancy Shape Cut Grade from AGS
http://www.diamonds.net/News/NewsItem.aspx?ArticleID=11617
“This is the industry’s first scientific cut grade for the princess cut.”

Scientific Recognition for AGS Cut Grade
http://www.diamonds.net/news/NewsItem.aspx?ArticleID=19529
“Recognition and backing by the scientific community.”

Neither of these links is anything except AGSL describing their system. The second link refers to a scientific journal called Optical Engineering which is nowhere I can find. Even if we do find it, one journal article is by no means conclusive.
Again, no problem to disagree. But I ask that we maintain respect for the hard work and achievements of our peers.

I do not believe that respecting the work done includes ignoring some very common sense drawbacks to the results.
I am not disrespecting anyone. I honestly believe that any scientist who's interested in advancing science will welcome reasonable questions about the work. I also believe AGSL would love to find legitimate methods to broaden the usage of their products. I am familiar with the main people there- and my impression is that AGSL is continually refining their ideas on light performance. Discussion like this can actually help.

 

[John P]

I think it is quite safe to say the ray tracing approach is quite scientific.

That's the point I'm making. The approach and details can be debated.

 

[Texas Leaguer]

I think it is quite safe to say the ray tracing approach is quite scientific. What is questionable is how the different grades equate to beauty. Obviously with the linear scale from 0-10, a consumer would assume a 0 is more beautiful than a 1, which is equally more beautiful than a 2, which is equally more beautiful than a 3, and so on and so on.

The grading looks at objective measures such as leakage, contrast, etc and penalizes according to the presence of "deficits". One would assume more of those AGS "deficits" would equate to a less beautiful diamond. Human perception would suggest otherwise, as certainly there are loads of people whose eyes would gravitate towards a diamond that is anything but "ideal" according to those who came up with the AGS system.

This is why, in my opinion, human observations should somehow be taken into account. It is fine to come up with a set of grades based off the science your instruments are capable of, but before implementing it you should be sure it agrees for the most part with humans perceptions. Duplicating the power and versatility of the human eye with science is an uphill battle. Trying to trick the eye into thinking something is more beautiful because it has a better cut grade will fail. The eye likes what it likes, no matter what any instrument might suggest.

The problem is, you can't show a consumer's eyes the various diamonds they are considering in every lighting environment they will encounter. Their preference between stones could change multiple times depending on where they are viewing them. Likewise, you can't grade a diamond in infinite lighting situations. At some point, you have to come up with a set standard for your grading. There will NEVER, however, be a standard for viewing environment. How can anyone possibly overcome the challenge of infinite viewing conditions AND replicate the power of the human eye with instruments? It is just not possible. I take my hat off to those who plug away at it though. And for what it is worth, I have seen videos of AGS 0, 1, and 2 princess cuts and my eyes did prefer 0 to 1 to 2 in those videos. Having said that, I do see where David is coming from when he criticizes the AGS 0-10 scale. Certainly it isn't perfect and not everyone will agree that it is in line with human perception of beauty. However, people are often led to believe that it is ironclad and that any stone that is AGS graded has a vastly superior chance to be beautiful.

P,
I am glad to see your participation. You always bring a balanced view to the discussion.

I agree with everything you have said. I think the thing that tends to get lost in this discussion is the fact that we are talking about cut analysis. While cut is almost universally understood to have the greatest impact on diamond beauty, it is not the only factor by any means. But a smart shopper wants to have access to the most detailed analysis possible when making a decision.

Yes, the AGSL system is stringent and the top grade excludes alot of beautiful diamonds. Understanding that means that there is nothing wrong with considering a diamond with AGS0 or 1 or 2. (The princess cut in the sample above that David characterized as 'rockin' is AGS 3). Could the AGS system have been broadened out to be more inclusive like the GIA system? Sure. But that was not the intent. The intent was to make small but important distinctions that would help consumers better understand their diamond and thereby be able to make better buying decisions.

The key is to put all of the information you have about a prospective diamond into your own personal decision matrix. If everything gets proper weight, a good decision will result.

 

[Rockdiamond]

I think it is quite safe to say the ray tracing approach is quite scientific.

That's the point I'm making. The approach and details can be debated.

Which is precisely what I have been doing.

 

[John P]

HI John!
I'll answer some below in blue

David, I hesitate to wade into this pond as it won't change anything. But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

INDUSTRY
http://www.diamonds.net/Magazine/Article.aspx?ArticleID=45475&RDRIssueID=117
“AGS has succeeded in bringing science to the forefront of diamond design”

I respect the following:

You may not believe our world is usually lit from above - the scientific system does. First, scientific systems don't "believe" anything. Science involves fact, not beliefs, or in this case, commercial concerns. IN terms of the world being lit from above- I can think of few viewing environments where that statement is surely true. Standing outside at noon. I can think of many environments where light is coming from many directions. Right now I'm sitting in my office and there's more light coming in a 45 degrees than directly overhead. Many places people look at diamonds have main lighting sources that are not directly overhead.
You may not believe people like to tilt diamonds back and forth - the scientific system does. We agree that tilt is crucial to viewing a diamond. That's why a single static ASET may need to be interpreted differently than a simplistic "Red is better than Green"
You may not believe 10 inches is a common viewing distance - the scientific system does. I agree that's a common distance.
You may not believe brightness is a performance priority - the scientific system does. I agree that brightness is a priority- but perceived brightness is by no means consistent from one individual to the next- and again, lighting comes into play
…Insert whatever else you think should be different or find “arbitrary.”

That’s all fine. Vive la difference. But your disagreement, or mine, doesn't invalidate the foundation, development, peer-review and published fact of this working metric, which is entirely based in repeatable science.

Fancy Shape Cut Grade from AGS
http://www.diamonds.net/News/NewsItem.aspx?ArticleID=11617
“This is the industry’s first scientific cut grade for the princess cut.”

Scientific Recognition for AGS Cut Grade
http://www.diamonds.net/news/NewsItem.aspx?ArticleID=19529
“Recognition and backing by the scientific community.”

Neither of these links is anything except AGSL describing their system. The second link refers to a scientific journal called Optical Engineering which is nowhere I can find. Even if we do find it, one journal article is by no means conclusive.
Again, no problem to disagree. But I ask that we maintain respect for the hard work and achievements of our peers.

I do not believe that respecting the work done includes ignoring some very common sense drawbacks to the results.
I am not disrespecting anyone. I honestly believe that any scientist who's interested in advancing science will welcome reasonable questions about the work. I also believe AGSL would love to find legitimate methods to broaden the usage of their products. I am familiar with the main people there- and my impression is that AGSL is continually refining their ideas on light performance. Discussion like this can actually help.

Forgive me David, but I must ask in all sincerity: Are you pulling my tail? We've engaged in many conversations over the years on this very topic. Every item in blue has a logical answer I believe you have either read before, or is clearly explained in the SPIE paper; which is not a "journal-article" but is an official publication of the optical engineering society following their industry peer-review of the AGS system. I honestly feel you already know this?

If you are re-setting the stage to re-hash old discussions with new participants that's fine. It's always stimulating to revisit. Regrettably, I genuinely lack the time to do all of it again right now.

 

[Rockdiamond]

Bryan:
This is what you wrote

Regarding the specific deductions of the samples alluded to, I was able to pull up the grading data on stone # 2. It had a GIA report and was marketed as a 'signature ideal' that was sent to AGSL for light performance testing. Ironically, though it is being represented as an ideal cut, it does not even get the top grade from GIA for symmetry. That is what I would say is a bit misleading.

Who marketed it as "signature ideal" and who made the decision to send it to AGSL?

I said that I've seen diamonds with ASET signatures that looked like that, and they were "kickin"- however I have never seen that stone, so I would not describe it specifically.

John-If you're too busy to participate, that's of course fine.
No, I am not familiar with SPIE paper. The points I'm bringing up have NEVER been answered to my satisfaction.
AS long as people are continually steered towards more costly diamonds based on "science" I will keep bringing up the reasons beauty, and diamond desirability are NOT scientifically quantifiable.
AS long as people are being told that cutters any cutters NOT adhering to AGSL standards are interested only in profit, not beauty, I will contest that.
Of course certain diamonds ARE worth more due to the precision of the cut.
But part of that is like a D being worth more than a J.
A D is not "scientifically better" than a J. It cost more and has less color.

An AGSL 0 princess cut might be worth more to some people- but it's because they find it more beautiful, not because it's scientifically better.

 

[John P]

John-If you're too busy to participate, that's of course fine.
No, I am not familiar with SPIE paper. The points I'm bringing up have NEVER been answered to my satisfaction.

David - I need to leave but took a few moments on your behalf:

The SPIE paper is referenced and linked in each thread below.
You've participated in all of them.

Memory lane. The below is a nice little list of dialogues, and a cool collection of reads for anyone interested.

Obstruction (2009)
https://www.pricescope.com/community/threads/obstruction.129821/

Is cut grading science or opinion? (2010)
https://www.pricescope.com/community/threads/is-cut-grading-science-or-opinion.138282/page-2

Diamond Cut Angles (2010)
https://www.pricescope.com/communit...tems-and-gaming-them-an-eternal-story.157859/

Crushed Ice Cushions…BAD? (2010)
https://www.pricescope.com/community/threads/crushed-ice-cushions-bad.148696/

Trade Participation on Pricescope (2010)
https://www.pricescope.com/community/threads/trade-participation-on-pricescope.149926/

Grading systems and ‘gaming’ them : An eternal story? (2011)
https://www.pricescope.com/communit...tems-and-gaming-them-an-eternal-story.157859/

What is the difference between cut grading and cut rejection? (2013)
https://www.pricescope.com/communit...between-cut-grading-and-cut-rejection.188888/

Discussion of green in an ASET image (2014)
https://www.pricescope.com/community/threads/discussion-of-green-in-an-aset-image.150479/

An interesting (to me) ASET comparison – JA vs. DiamCalc (2014)
https://www.pricescope.com/communit...-aset-comparison-ja-vs-diamcalc.205766/page-3

ASETs and fancy cuts (2014)
https://www.pricescope.com/community/threads/asets-and-fancy-cuts.204414/

GIA India – is this junk? (2014)
https://www.pricescope.com/community/threads/gia-india-is-this-junk.207237/

Light leakage, how can you tell in real life? (2014)
https://www.pricescope.com/community/threads/light-leakage-how-can-you-tell-in-real-life.203965/

Experts needed on diamond proportions. (2015)
https://www.pricescope.com/community/threads/experts-needed-on-diamond-proportions.210439/

 

[Texas Leaguer]

Bryan:
This is what you wrote

Regarding the specific deductions of the samples alluded to, I was able to pull up the grading data on stone # 2. It had a GIA report and was marketed as a 'signature ideal' that was sent to AGSL for light performance testing. Ironically, though it is being represented as an ideal cut, it does not even get the top grade from GIA for symmetry. That is what I would say is a bit misleading.

Who marketed it as "signature ideal" and who made the decision to send it to AGSL?

I said that I've seen diamonds with ASET signatures that looked like that, and they were "kickin"- however I have never seen that stone, so I would not describe it specifically.

John-If you're too busy to participate, that's of course fine.
No, I am not familiar with SPIE paper. The points I'm bringing up have NEVER been answered to my satisfaction.
AS long as people are continually steered towards more costly diamonds based on "science" I will keep bringing up the reasons beauty, and diamond desirability are NOT scientifically quantifiable.
AS long as people are being told that cutters any cutters NOT adhering to AGSL standards are interested only in profit, not beauty, I will contest that.
Of course certain diamonds ARE worth more due to the precision of the cut.
But part of that is like a D being worth more than a J.
A D is not "scientifically better" than a J. It cost more and has less color.

An AGSL 0 princess cut might be worth more to some people- but it's because they find it more beautiful, not because it's scientifically better.

David,
I feel it would be a violation of forum rules to name the company who supplied the sample stone. However, you can find it on our website if you are so inclined. My purpose in posting it was only in response to your suggestion that I could not or would not support a statement about LP deficits with actual data.

The optical engineering journal article I have personally pointed you to on numerous occasions, and it is linked in the article we have been discussing in this thread.

 

[Serg]

David, I hesitate to wade into this pond as it won't change anything. But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

INDUSTRY
http://www.diamonds.net/Magazine/Article.aspx?ArticleID=45475&RDRIssueID=117
“AGS has succeeded in bringing science to the forefront of diamond design”

I respect the following:

You may not believe our world is usually lit from above - the scientific system does.
You may not believe people like to tilt diamonds back and forth - the scientific system does.
You may not believe 10 inches is a common viewing distance - the scientific system does.
You may not believe brightness is a performance priority - the scientific system does.
…Insert whatever else you think should be different or find “arbitrary.”

That’s all fine. Vive la difference. But your disagreement, or mine, doesn't invalidate the foundation, development, peer-review and published fact of this working metric, which is entirely based in repeatable science.

Fancy Shape Cut Grade from AGS
http://www.diamonds.net/News/NewsItem.aspx?ArticleID=11617
“This is the industry’s first scientific cut grade for the princess cut.”

Scientific Recognition for AGS Cut Grade
http://www.diamonds.net/news/NewsItem.aspx?ArticleID=19529
“Recognition and backing by the scientific community.”

Again, no problem to disagree. But I ask that we maintain respect for the hard work and achievements of our peers.

re:But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

1)I did not find anything about Cut Grading in Dr.Sasian article .
2) AGSL System and Dr. Sasian article is not same. it's are different stories. Nobody explained connection between raytracing research and human observation
3) AGSL never published proof , tests for AGSL Cut grading system. there were not published rules which explain selected boundary between AGS0 and AGS1( for round, princess).

May be AGSL is good system, but this system had not been proof in scientific way in scientific tradition.
in same time I do not see reason why Cut grading system( or any other grading system, Wine grading system for example) has to be proof in scientific articles.

Science is necessary to design good cuts, but grading is different story. Taste , traditions are very important parts for High End cuts.

 

[Rockdiamond]

Serg has really hit the nail right on the head. The grading system is great. I don't happen to agree with it when we're talking about princess cuts. But that is not the issue.
Advertising diamonds getting the top grade as scientifically better is misleading to consumers. This forum is supposed to be about consumer education. Confusing science with subjective judgments goes against that goal.

John – the points that I raised here were never suitably responded to the old contentious threads you linked to. Looking back, I surely have learned a lot. Remember, the paper you're referring to was written in 2007 – do you believe that paper to be the last word? Or is it possible that the authors might have to continue doing research and advanced their ideas. Maybe if it was written today we have different conclusions.

Bryan- of course I do not encourage you to break forum rules. I am confused though. You wrote an article with the picture of princess cuts asets and called them deficient. Then here you stated that someone submitted that diamond to AGS because they believed that it would earn ideal light performance.
Was the stone deficient or did it look great? The aset image seems to indicate the stone that would be pretty.

 

[Karl_K]

We can debate the science of the AGS system for the next 10 years but one thing is clear to me.
It has prompted some cutters to pay more attention to proportion sets and use precision cutting processes to produce some really nice princess cuts that would not have been produced otherwise

 

[Texas Leaguer]

Serg has really hit the nail right on the head. The grading system is great. I don't happen to agree with it when we're talking about princess cuts. But that is not the issue.
Advertising diamonds getting the top grade as scientifically better is misleading to consumers. This forum is supposed to be about consumer education. Confusing science with subjective judgments goes against that goal.

John – the points that I raised here were never suitably responded to the old contentious threads you linked to. Looking back, I surely have learned a lot. Remember, the paper you're referring to was written in 2007 – do you believe that paper to be the last word? Or is it possible that the authors might have to continue doing research and advanced their ideas. Maybe if it was written today we have different conclusions.

Bryan- of course I do not encourage you to break forum rules. I am confused though. You wrote an article with the picture of princess cuts asets and called them deficient. Then here you stated that someone submitted that diamond to AGS because they believed that it would earn ideal light performance.
Was the stone deficient or did it look great? The aset image seems to indicate the stone that would be pretty.

I did not say that. Please be careful not to misquote people on the forum.

 

[Rockdiamond]

Hi Karl,
That is great if you like the proportion set. Personally, I am thrilled that many cutters have ignored the AGS and cut other types of princess cuts that I think are prettier.
It would be truly a shame if diversity was lost simply to have everyone cut everything to look the same.

 

[Texas Leaguer]

David, I hesitate to wade into this pond as it won't change anything. But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

INDUSTRY
http://www.diamonds.net/Magazine/Article.aspx?ArticleID=45475&RDRIssueID=117
“AGS has succeeded in bringing science to the forefront of diamond design”

I respect the following:

You may not believe our world is usually lit from above - the scientific system does.
You may not believe people like to tilt diamonds back and forth - the scientific system does.
You may not believe 10 inches is a common viewing distance - the scientific system does.
You may not believe brightness is a performance priority - the scientific system does.
…Insert whatever else you think should be different or find “arbitrary.”

That’s all fine. Vive la difference. But your disagreement, or mine, doesn't invalidate the foundation, development, peer-review and published fact of this working metric, which is entirely based in repeatable science.

Fancy Shape Cut Grade from AGS
http://www.diamonds.net/News/NewsItem.aspx?ArticleID=11617
“This is the industry’s first scientific cut grade for the princess cut.”

Scientific Recognition for AGS Cut Grade
http://www.diamonds.net/news/NewsItem.aspx?ArticleID=19529
“Recognition and backing by the scientific community.”

Again, no problem to disagree. But I ask that we maintain respect for the hard work and achievements of our peers.

re:But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

1)I did not find anything about Cut Grading in Dr.Sasian article .
2) AGSL System and Dr. Sasian article is not same. it's are different stories. Nobody explained connection between raytracing research and human observation
3) AGSL never published proof , tests for AGSL Cut grading system. there were not published rules which explain selected boundary between AGS0 and AGS1( for round, princess).

May be AGSL is good system, but this system had not been proof in scientific way in scientific tradition.
in same time I do not see reason why Cut grading system( or any other grading system, Wine grading system for example) has to be proof in scientific articles.

Science is necessary to design good cuts, but grading is different story. Taste , traditions are very important parts for High End cuts.

Hi Serg,
I think your response contains a key concept that is a stumbling block for some in this discussion. The word “proof”.

A system or methodology can be scientifically rigorous without necessarily producing “proof”. Before we were able to take pictures of Pluto, early astronomers used rigorous scientific techniques to infer its existence.

Nor does a scientific methodology necessarily set out to prove certain things. Such as the taste aspects that you refer to. I think you will find throughout all the AGS published articles regular reference to the need to allow for taste. And in this respect, I think you are correct that the grading aspect of the system does not need to be proven in order to be useful.

While the GIA system was developed in conjunction with a very large survey (taste test), I don’t think you would call it more scientifically rigorous than the AGS system. With much less granularity in their grading structure, one would expect it to be easier to distinguish between EX and VG than it would to distinguish between AGS 0 and AGS1.

But the goal of the AGS system was to make more precise distinctions between performance levels. And to be able to do it on an individual stone basis in a consistent and repeatable way. That objective was achieved.

While everyone will admit the AGS system is not perfect, it represents a major leap forward that can be and will be built upon. And the research that you and your colleagues conduct will no doubt continue to contribute greatly to further advancements in the field.

 

[Texas Leaguer]

We can debate the science of the AGS system for the next 10 years but one thing is clear to me.
It has prompted some cutters to pay more attention to proportion sets and use precision cutting processes to produce some really nice princess cuts that would not have been produced otherwise

Succinct and insightful as usual Karl. If there can be "proof" that a methodology is valid and useful this would be it.

 

[Rockdiamond]

Regarding the specific deductions of the samples alluded to, I was able to pull up the grading data on stone # 2. It had a GIA report and was marketed as a 'signature ideal' that was sent to AGSL for light performance testing. Ironically, though it is being represented as an ideal cut, it does not even get the top grade from GIA for symmetry. That is what I would say is a bit misleading.

Here is exactly what you wrote – I am still confused. You used images of the aset the stone as a demonstration of a princess cut with deficits. Someone, not you, submitted this diamond to AGS because they believed it had ideal performance… Is that correct so far?

 

[Texas Leaguer]

Regarding the specific deductions of the samples alluded to, I was able to pull up the grading data on stone # 2. It had a GIA report and was marketed as a 'signature ideal' that was sent to AGSL for light performance testing. Ironically, though it is being represented as an ideal cut, it does not even get the top grade from GIA for symmetry. That is what I would say is a bit misleading.

Here is exactly what you wrote – I am still confused. You used images of the aset the stone as a demonstration of a princess cut with deficits. Someone, not you, submitted this diamond to AGS because they believed it had ideal performance… Is that correct so far?

No, you are not correct so far. Because you are making an interpretation of what I said.

 

[Rockdiamond]

Bryan- could you please clarify the statement of yours that I quoted today?
Are you still claiming the stone has deficits?

 

[Texas Leaguer]

Bryan- could you please clarify the statement of yours that I quoted today?
Are you still claiming the stone has deficits?

Yes the stone has deficits. And the AGS LP data indicates what they are.

As I said before, I will not go into further detail about this particular sample here as it would constitute a violation of forum rules. If you are interested to learn more you can find it pretty easily on our website where we are not subject to the same constraints.

 

[Rockdiamond]

Bryan- you're the one who included the stone in a PS article- and referred to it here . If that's a violation of forum rules the horse has left the barn.
I have no idea how to find the stone on your site.
You're telling us there's deficit s in the stone. Are these deficits described on your site?
Is it possible that other viewers might not see these aspects as deficits?
Is there something in the aset you can point to that highlights these deficits?
Or is it possible that the word "deficit"'is entirely misused in describing this diamond?

 

[Serg]

David, I hesitate to wade into this pond as it won't change anything. But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

INDUSTRY
http://www.diamonds.net/Magazine/Article.aspx?ArticleID=45475&RDRIssueID=117
“AGS has succeeded in bringing science to the forefront of diamond design”

I respect the following:

You may not believe our world is usually lit from above - the scientific system does.
You may not believe people like to tilt diamonds back and forth - the scientific system does.
You may not believe 10 inches is a common viewing distance - the scientific system does.
You may not believe brightness is a performance priority - the scientific system does.
…Insert whatever else you think should be different or find “arbitrary.”

That’s all fine. Vive la difference. But your disagreement, or mine, doesn't invalidate the foundation, development, peer-review and published fact of this working metric, which is entirely based in repeatable science.

Fancy Shape Cut Grade from AGS
http://www.diamonds.net/News/NewsItem.aspx?ArticleID=11617
“This is the industry’s first scientific cut grade for the princess cut.”

Scientific Recognition for AGS Cut Grade
http://www.diamonds.net/news/NewsItem.aspx?ArticleID=19529
“Recognition and backing by the scientific community.”

Again, no problem to disagree. But I ask that we maintain respect for the hard work and achievements of our peers.

re:But I must say it seems disingenuous to deny the achievements of Dr. Sasian, the University of Arizona, the AGS Laboratories and the Society of Optical Engineers: The AGSL system is scientific.

1)I did not find anything about Cut Grading in Dr.Sasian article .
2) AGSL System and Dr. Sasian article is not same. it's are different stories. Nobody explained connection between raytracing research and human observation
3) AGSL never published proof , tests for AGSL Cut grading system. there were not published rules which explain selected boundary between AGS0 and AGS1( for round, princess).

May be AGSL is good system, but this system had not been proof in scientific way in scientific tradition.
in same time I do not see reason why Cut grading system( or any other grading system, Wine grading system for example) has to be proof in scientific articles.

Science is necessary to design good cuts, but grading is different story. Taste , traditions are very important parts for High End cuts.

Hi Serg,
I think your response contains a key concept that is a stumbling block for some in this discussion. The word “proof”.

A system or methodology can be scientifically rigorous without necessarily producing “proof”. Before we were able to take pictures of Pluto, early astronomers used rigorous scientific techniques to infer its existence.

Nor does a scientific methodology necessarily set out to prove certain things. Such as the taste aspects that you refer to. I think you will find throughout all the AGS published articles regular reference to the need to allow for taste. And in this respect, I think you are correct that the grading aspect of the system does not need to be proven in order to be useful.

While the GIA system was developed in conjunction with a very large survey (taste test), I don’t think you would call it more scientifically rigorous than the AGS system. With much less granularity in their grading structure, one would expect it to be easier to distinguish between EX and VG than it would to distinguish between AGS 0 and AGS1.

But the goal of the AGS system was to make more precise distinctions between performance levels. And to be able to do it on an individual stone basis in a consistent and repeatable way. That objective was achieved.

While everyone will admit the AGS system is not perfect, it represents a major leap forward that can be and will be built upon. And the research that you and your colleagues conduct will no doubt continue to contribute greatly to further advancements in the field.

Bryan,
lets consider Weather . There are good and bad weather. but what Good weather is?
for example You develop Thermometer , measure with high accuracy the temperature one time per day then grade weather for each day .
you decided that best weather for you was in year X, 1st August. temperature was 25 degree Celsius ( 77 Fahrenheit) at 10:00 am.
if other day has same temperature +-2 degree, it is Ideal grade. If temperature 18-23, 27-32 then weather is Very Good.
can you do statement about scientific proof Weather grading system if you just publish nice article about new instrument( Thermometer )?
How is about weather during mountain ski holidays ( sunny day) or summer holiday in California ?
How is about wind, humidity , seasons ,habits..?
Is thermometer accuracy 0.1 degree most important factor for precise distinction between Ideal and very good weather?
Is 25 degree warm enough for people from India, Egypt ? Is 25 degree in city is same as 25 degree in forest?, Beach?
will grade based on temperature only always helpful and correct?

 

[Serg]

Bryan,
do you prefer see in Forecast Weather Grade instead information about temperature?

 

[Rockdiamond]

Bryan- the particulars of the stone don't really matter.
Serg has really provided the best analogy I've ever heard.
Using the weather analogy:
If Florida wants to advertise that the state boasts "ideal weather' they are free to do so. Even to claim that scientific evidence backs up the claim. People are used to such claims made in ads.
But if they were to make the same claim on an open forum dedicated to unbiased weather information it's likely that the claim would be disputed.
I'm not disputing the beauty of stones earning the AGSL "ideal" label. And never have.
But I have continually found the usage of terms like " light performance" and associating science with the cut grade here to be misinforming to consumers.

 

[gm89uk]

Hi, I've been following this discussion and finding it very interesting!

I am however failing to understand the weather analogy. People may have different preferred temperatures and that is subjective to each individual. For someone a temperature of 14 may be ideal, but only when they're jogging and on another day 23 may be spot on. Someone else entirely they may always like a higher temperature. However a diamond that reflects light in 1 environment will reflect light again in another, especially when the initial testing environment is well controlled based on the common angles and viewing distances

To my humble understanding, with light performance, more light return is never a bad thing. When observing a diamond, you would only pick one with less light return than one with better light performance, if the diamond makes up for it in another way, that adds to its subjective beauty. Such as someone preferring a deeper cut, or scintillation.

An extreme example is why would anyone pick a princess or a RB? A RB will have more light return but the compromise is the subjective beauty and taste of shape difference.

However once those compromises are accounted for, I believe light return is something anyone would want to maximise.
So a hot day may suck for some and rock for others, but everyone wants the brightest diamond they can get within the constraints they want, such as selecting the best princess they can get, or oval, or the best deep cut RB that still provides the best possible light performance.

I think another question is, does a diamond having excellent measured light return ever mean that it compromises another attribute of a diamond, that one may regard as appealing or beautiful?

 

[Serg]

Hi, I've been following this discussion and finding it very interesting!

I am however failing to understand the weather analogy. People may have different preferred temperatures and that is subjective to each individual. For someone a temperature of 14 may be ideal, but only when they're jogging and on another day 23 may be spot on. Someone else entirely they may always like a higher temperature. However a diamond that reflects light in 1 environment will reflect light again in another, especially when the initial testing environment is well controlled based on the common angles and viewing distances

To my humble understanding, with light performance, more light return is never a bad thing. When observing a diamond, you would only pick one with less light return than one with better light performance, if the diamond makes up for it in another way, that adds to its subjective beauty. Such as someone preferring a deeper cut, or scintillation.

An extreme example is why would anyone pick a princess or a RB? A RB will have more light return but the compromise is the subjective beauty and taste of shape difference.

However once those compromises are accounted for, I believe light return is something anyone would want to maximise.
So a hot day may suck for some and rock for others, but everyone wants the brightest diamond they can get within the constraints they want, such as selecting the best princess they can get, or oval, or the best deep cut RB that still provides the best possible light performance.

I think another question is, does a diamond having excellent measured light return ever mean that it compromises another attribute of a diamond, that one may regard as appealing or beautiful?

Diamond Beauty is not only Light Return. Fire and other Things are very important too.
Highest Light Return and Highest Fire are not possible in one diamond.
Brilliancy is not just Light Return and static contrast.
May Be AGSL has good "Thermometer" to measure Light Return, but they have not good instrument to measure Fire, Brilliancy, Scintillation.
the easiest proof for above statement is AGSL grades for diamond with different size: 0.1ct, 1ct, 10ct AGS 0 diamonds have same Fire grade.
You can easy check that these diamonds have different Fire.
My analogy was about grading system rules, that even precise instruments are not enough to build good grading system for Human perception.
if we speak about AGLS instruments they have not enough precise instruments to measure all important aspects of diamond beauty .
better analogy for AGSL grading system is :
they measure Illuminance( sunlight, solar radiation) at 10:00 am , then grade weather by Illuminance and reference illuminance in X year 1st August at 10:00 am.
they use very precise instrument and standard conditions to measure Illuminance.
if they need grade weather in other place( other cut) they select manually best day for other place and measure illumination reference for this place .
they have to use different Illumination references for different places because instead Temperature(Brilliancy) they measure Illuminance ( LightReturn).
Then sellers of weather forecast grades do statement :
Our grade is scientific proof because the Lab use scientific instrument to measure Illuminance , you can read articles about this instrument in ...

in same time I am agree that :
Weather perception depends from temperature, temperature depends from sunlight( Illuminance, solar radiation) .
Diamond Beauty depends from Brilliancy, Brilliancy depends from Light return.

 

[Rockdiamond]

Hi, I've been following this discussion and finding it very interesting!

I am however failing to understand the weather analogy. People may have different preferred temperatures and that is subjective to each individual. For someone a temperature of 14 may be ideal, but only when they're jogging and on another day 23 may be spot on. Someone else entirely they may always like a higher temperature. However a diamond that reflects light in 1 environment will reflect light again in another, especially when the initial testing environment is well controlled based on the common angles and viewing distances

To my humble understanding, with light performance, more light return is never a bad thing. When observing a diamond, you would only pick one with less light return than one with better light performance, if the diamond makes up for it in another way, that adds to its subjective beauty. Such as someone preferring a deeper cut, or scintillation.

An extreme example is why would anyone pick a princess or a RB? A RB will have more light return but the compromise is the subjective beauty and taste of shape difference.

However once those compromises are accounted for, I believe light return is something anyone would want to maximise.
So a hot day may suck for some and rock for others, but everyone wants the brightest diamond they can get within the constraints they want, such as selecting the best princess they can get, or oval, or the best deep cut RB that still provides the best possible light performance.

I think another question is, does a diamond having excellent measured light return ever mean that it compromises another attribute of a diamond, that one may regard as appealing or beautiful?

Great questions - they highlight how this misinformation impacts perception.
A few key points:
100% light return equals a mirror. So more light return is not necessarily better if what we want to see is a sparkly diamond.
Will "better" light return look better no matter the lighting environment.
No. A given diamond cutting style will have different reactions to different lighting. Some cuts look better in lower lighting for example. It is said that antique diamonds, cut in much lower light factories than we have today look better in candlelight than a modern round brilliant. Many "crushed ice" diamonds look better in direct sunlight as compared to an RBC. I have noticed both of these aspects myself.
Compromises- yes there are times that cutting to AGSL ideal standards yields a smaller looking diamond due to increased depth.

If you can convince people that more light return is better ( by scaring them with a term like "leakage" - or claiming that there are invisible "deficits") then you can get them to pay more for an "ideal" cut.
There's reasons an ideal cut may actually be worth more- but not scientific light measurements.

 

[Karl_K]

I think another question is, does a diamond having excellent measured light return ever mean that it compromises another attribute of a diamond, that one may regard as appealing or beautiful?

Yes that can happen and AGS actually accounts for that factor in some ways.
Originally there was too much of it built into the system that it actually was in some ways contradictory but a diamond can still be bright and not get AGS0.