AGS new cut grade system early 2005

[Garry H (Cut Nut)]

Marty AGS use DiamCalc to model their 3 colored ideal-scope type scope from 3D scans. That is the lighting format.

Re the GIA article on the "foundation" of their new system - do you think it is relevant to discuss here or on a new thread? (I think here is appropriate because of the ray tracing (oops - wash my mouth out - beams) stuff you guys are discussing.

But other issues may best be covered in a new thread.
Foreigners must wait for our copies

BTW Marty - it would be nice if you could write a review in english too

 

[adamasgem]

----------------
On 10/22/2004 3:54:57 AM Garry H (Cut Nut) wrote:

Marty AGS use DiamCalc to model their 3 colored ideal-scope type scope from 3D scans. That is the lighting format.

OH Could you please DEFINE that. Your statement is NO DEFINITION of their environment

Re the GIA article on the 'foundation' of their new system - do you think it is relevant to discuss here or on a new thread? (I think here is appropriate because of the ray tracing (oops - wash my mouth out - beams) stuff you guys are discussing.

It IS appropriate on this thread, because the subject is interrelated to what AGS did

But other issues may best be covered in a new thread.
Foreigners must wait for our copies

Why don't you have a copy FEDEXED to Sergey

BTW Marty - it would be nice if you could write a review in english too

Sorry Gary I can't speak or write in "Aussie: English

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

 

[Garry H (Cut Nut)]

You need to order a copy of the IDCC report Marty
Front page www.ideal-scope.com

Abstract The Concept of Angular Spectrum and its Relation
Assumptions and Aspects of the Forthcoming AGS Cut Grading System

It is no secret - there is not even a conspiracy. I am surprised you do not have more of their results - if you did you might even apreciate Aussie English Intuitive Observational Science

 

[adamasgem]

----------------
On 10/22/2004 5:25:49 PM Garry H (Cut Nut) wrote:

You need to order a copy of the IDCC report Marty
Front page www.ideal-scope.com

Abstract The Concept of Angular Spectrum and its Relation
Assumptions and Aspects of the Forthcoming AGS Cut Grading System

It is no secret - there is not even a conspiracy. I am surprised you do not have more of their results - if you did you might even apreciate Aussie English Intuitive Observational Science

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

Well Gary Is this false and deceptive advertising.

It was my understanding that the AGS presentation wasn't being released. Correct me if I am wrong.

 

[Garry H (Cut Nut)]

Not correct.
We were allowed to publish all the material we were given.
What you want to know is there.

You can model their environment in DiamCalc the same way you can model a Gilbertsonscope image if you have the know how (and since I can do it with no MIT qualifications, you probably could master it too).

 

[adamasgem]

----------------
On 10/22/2004 7:53:16 PM Garry H (Cut Nut) wrote:

Not correct.
We were allowed to publish all the material we were given.
What you want to know is there.

You can model their environment in DiamCalc the same way you can model a Gilbertsonscope image if you have the know how (and since I can do it with no MIT qualifications, you probably could master it too).----------------

I'll have to check with Pete on that as soon as he gets back from his vacation.

Gary, I don't want to use DiamondCalc, I want enough info to model it myself in forward MonteCarlo raytrace.

I do have their "color zones" and head model they supposedly used, but no clear definition of the illuminant, and spatial intensity variation, if any.

I do have their JA presentation and I'll check that to see if it contains the info I seek. Why don't you be a nice guy and send the conference material to me

Or do I have to pay you for it.

Afterall, it is for a good cause.

 

[Serg]

----------------
On 10/22/2004 5:45:15 PM adamasgem wrote:

Well Gary Is this false and deceptive advertising.

It was my understanding that the AGS presentation wasn't being released. Correct me if I am wrong.
----------------

Marty,

We never published the "false and deceptive advertising".
You are not correct.

 

[Garry H (Cut Nut)]

AGS did not give us their full presentation to print, but they gave permission to use all the material that they had given us.

Marty it cost the three of quite a lot of our own money to host the conference. It was a good cause we reasoned. A very small print run of a journal with very high print quality is very costly (and time consuming) to produce. We are asking $40, and it seems quite reasonable.

You could try to bot a copy from Michael Cowing or Bruce Harding?

(Do you know what 'bot' means?)

 

[adamasgem]

----------------
On 10/23/2004 7:44:50 AM Garry H (Cut Nut) wrote:

AGS did not give us their full presentation to print, but they gave permission to use all the material that they had given us.

That's a real definative statement

Marty it cost the three of quite a lot of our own money to host the conference. It was a good cause we reasoned. A very small print run of a journal with very high print quality is very costly (and time consuming) to produce. We are asking $40, and it seems quite reasonable.

Probably so, you should have published it as a pdf

You could try to bot a copy from Michael Cowing or Bruce Harding?
(Do you know what 'bot' means?)----------------
I can guess, but I won't do it

 

[adamasgem]

----------------
On 10/23/2004 3:10:03 AM Serg wrote:

----------------
On 10/22/2004 5:45:15 PM adamasgem wrote:

Well Gary Is this false and deceptive advertising.

It was my understanding that the AGS presentation wasn't being released. Correct me if I am wrong.
----------------

Marty,
We never published the 'false and deceptive advertising'.
You are not correct.
----------------

Sergey.. No offense to you, but when I asked about the AGS presentation, I was told it wasn't being released. I didn't know there was a "subset" in the conference notes. I generally find abstacts and most "subsets" technically useless.

 

[adamasgem]

Sergey: Let's get back to some technical discussions..

What bothered me regarding GIA's original "brillaince" study was that the distributional statistics of WLR (about the mean value published) seemed to suggest that the "answer" one got was somewhat marginally usefull.

The histogram here is a typical result from hemispherical lighting, and indicates the culmulative distribution in green, and the mean value in red. Not a great confidence builder in all the contour map data presented, but then again, it represents an averaging over viewer positions per-se

Now in the reverse ray trace methodology of MSU (and now probably GIA and AGS, because of the huge computational time burden in forward Ray Tracing), it appears that one has to settle for a fixed viewer position to arrive at a "metric". But in my opinion, fixed viewer positions have the tendency to potentially alias any global result (contour map), just as "environment" does.

Question: does MSU have data they can present which compared, in a contour map sense, or for a limited "set" of stones like those defined in the GIA article, the relative performance metric one obtains vs viewer position.?

For Gary, I'll put it in simpler terms: "for the same lighting environment, is one stone from a "set" always "better" regardless of the viewer's perspective"

 

[adamasgem]

My second question has to do generically with the "environment" issue I have been raising. I ran the initial GIA set of stones for hemispherical lighting of different solid angles from the zenith. It is obvious from tehse data, that diamonds have their highest light return efficiency when the light is from overhead.

What is also obvious, at least to me, is that one could "tailor" an environment which minimizes the distinction between stones. Take for example in the graph shown, if the hemispherical lighting was set to 0 to 45 degrees, there is little distinction between the WLR metrics.

 

[adamasgem]

As I have been reading the new G&G, my blood pressure is going up at what the industry and the public will be force fed regarding appropriateness of the new GIA "brightness" model, based on a one eyed, big headed, static viewer overhead of the diamond.

I looked at their additional tables in the G&G data depository as to the "hemispheres" they used to try to correlate their "observations" to lighting model, and it is no wonder why none correlated, none of the "models" come close a real observation scenario.

When GIA came out with their initial Brilliance article, one of the thing i DID agree with was their use of a cosine squared weighting to take into account that the viewer will rock the stone and observes and makes "brightness" decisions based on an "overall" impression of the stone.

Additionally, I see NO observation conditions in the real world other than sitting a stone on perfectly black absorber which match
the "black hole at the girdle plane" criteria that GIA settled on, nor do I see a uniform intensity lighting environment suggested by their use of their "hemispheres". And they even comment on it.

Of course, their cycloptic "model" lends itself to the use MUCH MUCH faster reverse ray tracing techniques for "analyses". Is that the NEW driving force???

 

[Serg]

----------------
On 10/24/2004 1:36:01 PM adamasgem wrote:



Of course, their cycloptic 'model' lends itself to the use MUCH MUCH faster reverse ray tracing techniques for 'analyses'. Is that the NEW driving force???

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

Reverse tracing is absolutely correct if your goal is computing what Human see.

For this task reverse tracing has accuracy equal direct tracing but MUCH MUCH faster.

You can use cycloptic 'model' or stereo model. It is YOUR choice.


WLR metric ( sum all outgoing light) is very bad that is why I never will calculate this metric for cut grading study .
Verification tests should have different principle( you should have possibility check by real experiment for, example by photo)

Some explanation why WLR is bad metric you could find http://www.cutstudy.com/cut/english/grading1/8.htm

In Tuesday I will published more clear example* and more explanation about my verification policy.


Marty please do not mislead audience.

Reverse tracing in nice instrument.
If any instrument need MUCH MUCH more time it is not mean this instrument is better.

*PLease think about 90 degree prism( or NailHead diamond), hemisphere light with head.
Could anybody publesh here before Tuesday Why WLR will give incorrect result for such condition?
The prize for best correct answer is Diamcalc and IDCC proceedings.

 

[strmrdr]

If I may make a fool of myself again I have a question.
Marty hit on something that bugs me.
Thats position.
Why hasnt a study been done to see how the majority of
people actualy look at diamonds on the hand and model
that instead of argueing over head shadow which isnt
even an issue on the hand.

Also as Iv seen in gemstones and diamonds once
it is set it can take a radicaly different look than unset.

Wouldnt it be much more realistic to model lets say in a
simple 4 prong tiffany style setting in a real world position?

The majority of people when admiring there rings
look at them in front of them and at an angle.
Some arm lenth some bring it closer.
Not one brought it up to their chest and looked down on it.

 

[strmrdr]

Sergey,
http://www.cutstudy.com/cut/english/grading1/9.htm
"(If the observer views the mirror with two eyes, the number of visible reflections fluctuates within the same limits, but the average number will be two times as large as that in the case of single-eye viewing. This is because each reflection could be detected by either the right or the left eye, which are spatially separated. When your eyes see the two spots on the flat mirror your brain merges them into one spot. But when you look at two mirrors and each eye sees one reflection in each mirror the brain will perceive two reflections)."

Not necessarily.
That statement would have got a big red x on the optics exam I took in college.
It int that simple there are other factors than the one you mention..
With 2 eyes open someone might see more but not 2x.
Eye dominance comes into play here as well as other factors.
Some of the ones striking the non-dominanat eye will be ignored if the brain perceives than as already accounted for by the other eye or if they appear to come from close enough to the same place.
The human eye is not a pure stereographic system.
It is a mixed system more so in some people that others.
This has been a huge problem delaying the introduction of 3d movies and tv's that actually work.

Edit to add: with just 2 it might work as stated but when you consider in the context of diamonds it doesnt scale due to the reasons I stated.

 

[Serg]

----------------
On 10/24/2004 5:36:07 PM strmrdr wrote:
The human eye is not a pure stereographic system.
blockquote>


First Part:

I read this your statement. I think this statement is not full correct.

Do you know more pure stereographic system then human system? human has on of the best (may be ) best stereographic system. Sometimes we could not understand reasons of human systems, but it should not mean what system is wrong, not a pure...

Second Part:

This your statement is not important for my statement.


CHECK my statement:
Took diamond, 1-3 small lights in dark room, distances between diamond and you,
between diamond and light should 1-3 meters.

Count up flash for two open eyes, left open eye only, for right open eye. Publish result.

P/s It is not main problem of WLR

 

[Serg]

Eye( ant Brain to) is not pure science instrument.
Eye is not pure photometry instrument.

All this and similar statements are correct.
But Eye is BEST instrument currently for Human task. Its properties depend from condition, task.

Eye( Brain) is adaptive. What is why it is not pure .., but best for Human.

 

[adamasgem]

----------------
On 10/24/2004 3:03:30 PM Serg wrote:

----------------
On 10/24/2004 1:36:01 PM adamasgem wrote:



Of course, their cycloptic 'model' lends itself to the use MUCH MUCH faster reverse ray tracing techniques for 'analyses'. Is that the NEW driving force???

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

Reverse tracing is absolutely correct if your goal is computing what Human see.

For this task reverse tracing has accuracy equal direct tracing but MUCH MUCH faster.

You can use cycloptic 'model' or stereo model. It is YOUR choice.

I agree with that Sergey, but one needs to examine and average somehow multiple viewpoints, not just one, that is why I liked the original WLR approach of GIA. I don't agree with the addition of glare, because the glare effect is HIGHLY subject to the viewpoint, and is only a function of the crown facets.


WLR metric ( sum all outgoing light) is very bad that is why I never will calculate this metric for cut grading study .
Verification tests should have different principle( you should have possibility check by real experiment for, example by photo)

Some explanation why WLR is bad metric you could find http://www.cutstudy.com/cut/english/grading1/8.htm

In Tuesday I will published more clear example* and more explanation about my verification policy.


Marty please do not mislead audience.

Reverse tracing in nice instrument.
If any instrument need MUCH MUCH more time it is not mean this instrument is better.

Sergey I just don't believe that a single snapshot from a static observer is the way to evaluate a diamond

*PLease think about 90 degree prism( or NailHead diamond), hemisphere light with head.
Could anybody publesh here before Tuesday Why WLR will give incorrect result for such condition?

Sounds like you are talking about a retro reflector which, with a head, will give a good WLR but not return anything to the observer

The prize for best correct answer is Diamcalc and IDCC proceedings.----------------

 

[adamasgem]

----------------
On 10/24/2004 5:14:45 PM strmrdr wrote:

If I may make a fool of myself again I have a question.
Marty hit on something that bugs me.
Thats position.
Why hasnt a study been done to see how the majority of
people actualy look at diamonds on the hand and model
that instead of argueing over head shadow which isnt
even an issue on the hand.

I believe GIA did something in their studies like that, but most of the "observations" apparently were weighted as to how the diamontaire looks at a stone in the "retail" environment

Also as Iv seen in gemstones and diamonds once
it is set it can take a radicaly different look than unset.

Wouldnt it be much more realistic to model lets say in a
simple 4 prong tiffany style setting in a real world position?

The majority of people when admiring there rings
look at them in front of them and at an angle.
Some arm lenth some bring it closer.
Not one brought it up to their chest and looked down on it.

You are right there, there are many physical "viewpoints" and lighting environments that can be used.

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

 

[strmrdr]

----------------
On 10/25/2004 12:56:33 AM Serg wrote:

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


CHECK my statement:

Took diamond, 1-3 small lights in dark room, distances between diamond and you,

between diamond and light should 1-3 meters.


Count up flash for two open eyes, left open eye only, for right open eye. Publish result.


P/s It is not main problem of WLR




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

Ok I did this.
With my .15ct h&a the flashes were too close together to get an accurate count.

On a signity star cz 6.5mm the results were different on every run.

1st,
left eye 2 bright flashes, right eye 2 bright
flashes 1 not as bright. Both eyes 2 bright flashes that are in the same position but a lot bigger If I looked hard could find the fainter one because I knew where to look.

2nd adjusted lights for more smaller flashes:
right eye 5 flashes, left eye 3 flashes both 6 flashes.

3rd run
put the brightest area of both lights on it:
right eye a lot of small flashes pretty much uncounable, left eye fewer but still uncountable flashes both eyes almost solid return and hard to tell individual flashes.

Conditions light was aprox 4 feet above diamonds/czs and aprox 1 foot over my head and to the left and right and I was looking down at an angle at the diamonds 3 feet away.
2 mini-mag lights with fresh batteries was the light source.
I wear thick glasses with the left eye having the stronger lenses.

So overall my results are inconclusive.
But at no time did I see twice as many flashes.

 

[Serg]

----------------
On 10/25/2004 2:31:27 AM adamasgem wrote:

I agree with that Sergey, but one needs to examine and average somehow multiple viewpoints, not just one, that is why I liked the original WLR approach of GIA. .

*PLease think about 90 degree prism( or NailHead diamond), hemisphere light with head.
Could anybody publesh here before Tuesday Why WLR will give incorrect result for such condition?

Sounds like you are talking about a retro reflector which, with a head, will give a good WLR but not return anything to the observer <img .



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

Marty , there is fun to read all text in one time . You should do choice: You want use a correct metric or the simple metric for calculation. What is your choice ?


re:Sergey I just don't believe that a single snapshot from a static observer is the way to evaluate a diamond

FYI. We use at least the 30 position for all range of parameters . For control tests we use 225 position.

see description our 1999 year work. http://www.cutstudy.com/cut/english/model_1.htm

 

[Serg]

Strmrdr,

What was distance from diamond to you?
It should be long distance 1-3 meters. otherwise left and right eyes could see same flashes.

Increasing the quantity of flashes is possible if eyes are seeing different flashes.

Please give 4 number for one test:

both eyes, left eyes, right eye, again both eyes.

Firstly use both eyes, It is very important!

 

[strmrdr]

distance was 3 feet or so right around 1 meter.
Its all the room I had in my bathroom which is the
only totaly dark room in the upstairs at my apartment.
I will try again tomorrow in the basement at a longer distance.
But again I fail to see what 10 feet(3+ meters) away has to do with real
world diamond viewing conditions.
Even my test was a greater distance than
Id normaly look at diamonds on my fingers.

Sorry If I sound like a broken record but I would like to see a study done using more realistic envirements,distances and viewing angles.

 

[strmrdr]

----------------
On 10/25/2004 2:39:07 AM adamasgem wrote:

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

I believe GIA did something in their studies like that, but most of the 'observations' apparently were weighted as to how the diamontaire looks at a stone in the 'retail' environment




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

That makes me want to barf because the diamonds that look best under that envirement may not be the best looking ones under real world on the hand conditions.

Anyway I will let you 2 get back to your discussion thanks to both of you for responding to my questions.

 

[Serg]

----------------
On 10/25/2004 3:35:27 AM strmrdr wrote:

distance was 3 feet or so right around 1 meter.
Its all the room I had in my bathroom which is the
only totaly dark room in the upstairs at my apartment.
I will try again tomorrow in the basement at a longer distance.
But again I fail to see what 10 feet(3+ meters) away has to do with real
world diamond viewing conditions.
Even my test was a greater distance than
Id normaly look at diamonds on my fingers.

Sorry If I sound like a broken record but I would like to see a study done using more realistic envirements,distances and viewing angles.




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

The brain "sees" number of flashes bigger or equal to what every eye sees individually in the conditions of dark room (and correspondingly dark diamond).
The maximum number of flashes visible by brain for static picture is the sum of flashes seeing by every eye individually.

This effect exists for any distance from eyes to diamond. I can see it perfectly from 40 cm as well (one of standard distances for diamond viewing, but it is not the only one standard distance). We tested this "rule" on different people and it works well. This is the reason why I concern myself with analysis of features of the stereovision.

It is necessary to have all different flashes for realization of extreme value of describing rule (namely total number of flashes is equal to sum of flashes which are observed by left and right separately). In case right and left eye sees the same flash the brain will consider it as one flash but not two.
The example with mirrors I specially created the conditions for extreme value of this rule: "the average number will be two times as large as that in the case of single-eye viewing." Before publication I spent a lot of time on choice between "two times" and "write: "almost two times". I don' pity about I risked. In our publications you can find many provocations which we knowingly made. We try to provoke to discussion. We didn't use false assertions as provocation.
Of course usually coefficient is less then two times. But even for one eye for dynamic picture you will see greatly more than one image of source. Quantity of images depends on parameters of mirrors, source and their position. WLR is always the same in any case. (One more provocation. I should add: "if we ignore changes in consequence of cos*cos". But a lot of quantity of reservations results in fact that it is difficult to see essence of problem. The essence is the brain "sees" number of flashes two times bigger then every eye. This assertion is important for step from mono to stereo-observation. After this we can calculate more exactly the coefficient between single-viewing and stereo-viewing).


Strmrdr,
Thanks that you read our article thoroughly.

 

[lma]

I am thinking of going to the diamond district in nyc to get a 1.5 carat diamond and a .60 round stone to match my diamond i have now, to make a three stone diamond ring. I want to know how to find a dealer i can trust and where to start when in nyc. should i try the diamond district or just go to tiffany's . I don't know if those stores in the diamond district are trust worthy or not. Any information would be helpful.
thanks,
lynne

 

[lma]

Do you know of any stores in the diamond district in nyc
i can trust to buy a 1.5 and a .60 round good quality diamond from. Do you like the diamond district stores or should i go to tiffany's.
thanks,
lynne

 

[lma]

----------------
On 9/15/2004 3:31:35 PM oldminer wrote:


Yes, approximately 37 percent more diamonds will fit the AGS 0 model than at present. No doubt, most of them will have a great light performance, much more consistent with eachother than under their old system, BUT not all of them will truly be as well cut if one looks at the craftmanship component of cut. While AGS has fixed their steep/deep issue, they have opened Pandora's box with shallow crown stones that have somewhat deeper pavilions. These diamonds Garry and AGS assure us will perform very well, but will they be as pleasing a product? They will cost less, up to 20% less to produce, as less rough goes to waste, but will they be as superior a product as a near Tolkowsky cut? It may be easier to convince the public than to convnce me or expert cutters. I view the AGS 0 system as having been too liberal before and, although changed, still overly liberal and excessively commercial. If you want a superior diamond, an AGS 0, under the present or the new strategy may not get you the very best possible stone and that's regrettable. An AGS 0 will be a very nice diamond, but may not be a top stone in every respect. What's the point of seeking the ultimate quality when it remains undefined or mixed up with 2nd and even 3rd tier gems?


Performance is one element of Ideal.

It takes more than light performance to create an 'Ideal' diamond although there is no question that without light performance being high, a diamond can't be an Ideal cut. There are people who will insist that light perfromance is all there is to 'ideal'. I say that is a wrong opinion.


Finish is a second component: The concept of proper facet shape, correct facet placement, facet matching, and a pleasing symmetrical outline are four elements necessary to consider and grade as 'excellent' if one is to have an 'Ideal' stone.


Parameters of cutting are the third component.

They define a diamond of proper depth to width ratio, sufficent crown angle for durability, sufficient but not excessively thick or thin girdle thickness, and the proper table and culet size range. These important aspects are not part of 'performance' or 'finish', but are essential, in my view, to defining the 'Ideal' diamond.


It would not be a difficult task for my lab to adopt using only the AGS system for grading, but I just feel that it is not the right system. Rather than just criticize, we are hard at work to bring proven scientific light performance information, combine it with AGA Cut Class grades and then include a very rigorous 'finish' grade for the consumer and the trade. Its easy to criticize and have nothing positive to offer. We hope that in a few weeks we will have some very viable and less problematic solutions. The 'Light Performance' and 'Finish' grading devices and software will be made available via Imagem, Inc. to all qualified labs and interested parties as part of their business plan. I have freely allowed the AGA Cut Class system to be accessed by anyone interested for many years, and hope to continue to offer it for free. AGA is going to put all three components into upcoming diamond reports. I think we will have a superior service to offer those who want the very best. We'll see how it goes.
----------------

I am looking into purchasing a 1.5 round diamond and a .60 round diamond to match my .60 diamond i have now, to make a 3stone diamond ring. We have been to local diamond stores in our home town and now are thinking of going to nyc diamond district.. Do you reccomend doing this, does it really pay off and are any of the stores trust -worthy.
any information wil be helpful.

thanks,
lynne

 

[adamasgem]

----------------
On 10/25/2004 3:07:06 AM Serg wrote:

----------------
On 10/25/2004 2:31:27 AM adamasgem wrote:

I agree with that Sergey, but one needs to examine and average somehow multiple viewpoints, not just one, that is why I liked the original WLR approach of GIA. .

*PLease think about 90 degree prism( or NailHead diamond), hemisphere light with head.
Could anybody publesh here before Tuesday Why WLR will give incorrect result for such condition?

Sounds like you are talking about a retro reflector which, with a head, will give a good WLR but not return anything to the observer <img .
Sergey, am I close regrading this..


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

Marty , there is fun to read all text in one time . You should do choice: You want use a correct metric or the simple metric for calculation. What is your choice ?
See below, a "correct metric". I never said I didn't agree with your methodology.


re:Sergey I just don't believe that a single snapshot from a static observer is the way to evaluate a diamond

FYI. We use at least the 30 position for all range of parameters . For control tests we use 225 position.

YES Sergey, I agree with you, but it would be nice for you to define the conditions used, including the lighting environment.

Your metric may be (it probably is

) much more appropriate than what GIA proposes, but it is hard to understand it in a vaccuum. How about a little more sunlight on it?

.
Look, you guys have a powerfull tool in DiamondCalc

, and are apparently much farther ahead of the pack in understanding than our industry "leaders" would have anyone believe.
The subtle thing is that both AGS and GIA apparently are going to try to sell proprietary software that will spit out a number, and I've very concerned with what appears to be a force-feeding of the "public" with "information" that might be just a little too pandering to the "trade". The "science" presented lately appears to be more about $$$$ and selling "paper".

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