AGS 2 or AGS 0 - The ''Candidate'' vs Parametric grades

[WinkHPD]

Date: 2/24/2007 4:54:20 PM
Author: Serg


Did you hear: I will HAPPY delete all from AGS in DC3.0

From one who loves Diamcalc and who is NOT an attorney, please do not do that.

Many of us really love having it there and removing it will make the program not as wonderful for us as it is now.

Wink

 

[adamasgem]

style="WIDTH: 99%; HEIGHT: 245px">Date: 2/24/2007 5:08:46 PM
Author: Serg
re:publish software that gives AGS_2005 ''parameters quality'' for conditions which were never published. Seems a software fix is in order?

from http://www.octonus.com/oct/products/3dcalc/standard/diamcalc_2-4.phtml

''The new AGS appraiser for Brilliant and Prince cuts is added. It is named AGS_2005. This appraiser provides estimation of the overall cut quality, using several cut parameters simultaneously. The parameters that are taken into account during stone appraisal are displayed in gray, red or green color. The red color means that it is necessary to decrease the parameter value to get to a better group, the green color suggests to increase the parameter value. There is also a special button ''Better group'' that changes all parameters of the stone to move it to a nearest better group. ''

What is color for diameter?

It is a SHAPE issue, the guidelines were issued for rounds...

 

[adamasgem]

Date: 2/24/2007 5:18:58 PM
Author: Wink

Date: 2/24/2007 4:54:20 PM
Author: Serg



Did you hear: I will HAPPY delete all from AGS in DC3.0

From one who loves Diamcalc and who is NOT an attorney, please do not do that.

Many of us really love having it there and removing it will make the program not as wonderful for us as it is now.

Wink

I agree with Wink, but just fix it please, so that DiamondCalc users are not mislead.

 

[strmrdr]

Date: 2/24/2007 5:37:17 PM
Author: adamasgem

Date: 2/24/2007 5:18:58 PM
Author: Wink

Date: 2/24/2007 4:54:20 PM
Author: Serg




Did you hear: I will HAPPY delete all from AGS in DC3.0

From one who loves Diamcalc and who is NOT an attorney, please do not do that.

Many of us really love having it there and removing it will make the program not as wonderful for us as it is now.

Wink

I agree with Wink, but just fix it please, so that DiamondCalc users are not mislead.

The only way he could provide accurate AGS grading is to licence the AGS software and integrate it.
Which goes back to the point I have been making all along charts are next to useless.

Serg''s point is that DC is a r&d tool not a diamond grading tool and that is where he wants his efforts to go.
Wrangling with AGS grading isn''t what he wants and or should be doing.
With that in mind personally I feel it might be better for everyone to drop the grading attempts but keep ASET and add ASET 40 both black and back lighted.

 

[michaelgem]

Strmrdr says and others also agree: “The only way he could provide accurate AGS grading is to licence the AGS software and integrate it. Which goes back to the point I have been making all along charts are next to useless.”

Consider this thought concerning Sergey and my request for updating the symmetric diamond cut grade estimation charts for completeness, and so that the AGS position may be correctly represented.

Protestation that it can’t be done because AGS’s system is non-parametric is a red herring (Definition for those in Rio Linda

: Something that draws attention away from the central issue.) It is also not true. For the symmetric case, both GIA and AGS methodologies reduce to be quite similar.
1. Both measure the diamond’s angles and proportions with a Sarin type device.

2. Since the diamond is perfectly symmetrical, GIA’s averaging makes no difference, since the parameters averaged are all the same. (Rounding vs. no rounding is a difference that can be side stepped by judicious choice of, for instance, 80% half length)

3. Both then model or have modeled the diamond from this similar Sarin data.

4. Both then apply their software metrics (or look up the stored application of their software metrics) to the diamond model to arrive at a grade.

Peter has already updated the cut grading guideline chart for the P41CR35T56 Ideal 0 combination that is currently labeled a 2. The same simply needs to be done for the rest of the charts data points. Not only can it be done, it is easy to do if you give the task to a programmer with the AGS-PGS software.

What Strmrdr finds next to useless is more than satisfactory to me, and I suspect Sergey as well. Updating those charts would correct the misrepresentation in the old cut grading guideline charts of AGS’s current range of Ideal 0.

Michael Cowing

 

[Serg]

Date: 2/24/2007 5:34:32 PM
Author: adamasgem

style="WIDTH: 99%; HEIGHT: 245px">Date: 2/24/2007 5:08:46 PM
Author: Serg
re:publish software that gives AGS_2005 'parameters quality' for conditions which were never published. Seems a software fix is in order?

from http://www.octonus.com/oct/products/3dcalc/standard/diamcalc_2-4.phtml

'The new AGS appraiser for Brilliant and Prince cuts is added. It is named AGS_2005. This appraiser provides estimation of the overall cut quality, using several cut parameters simultaneously. The parameters that are taken into account during stone appraisal are displayed in gray, red or green color. The red color means that it is necessary to decrease the parameter value to get to a better group, the green color suggests to increase the parameter value. There is also a special button 'Better group' that changes all parameters of the stone to move it to a nearest better group. '

What is color for diameter?

It is a SHAPE issue, the guidelines were issued for rounds...

Marty,
Please read again : "The parameters that are taken into account during stone appraisal are displayed in gray, red or green color. "It had been taken to account Pav. angle, Crown angle, Table, only( only 3 parameters)

Then we added penalty parameters like girdle and culet.

All other parameters: LG, Star facets, Second diameter, third diameter,painting,.. are out account.

( I do not like spend time for lock all these parameters, color marking is enough for proffesionals. Consumers can not use DC for grading. AGS consumers need paper or ASET image now)
It is simple tool had been added to DC in 2005 to help explan difference between old and new AGS grading systems.
It is not necessary more for AGS , I think

 

[adamasgem]

Date: 2/24/2007 11:01:54 PM
Author: michaelgem


What Strmrdr finds next to useless is more than enough to satisfy me, and I suspect Sergey as well. Updating those charts would correct the misrepresentation in the old cut grading guideline charts of AGS’s current range of Ideal 0.

Michael Cowing

Quit your whining, buy the PGS software, create the STL's in DC (or write your own software to do it), and do the job yourself if you are so interested in what you might find.. You always seem to want someone else to do the work for you.

You might be even able to reverse engineer the AGS methodology..

 

[michaelgem]

Some wish to project motivations as to my and Sergey’s purpose in requesting an update to the AGS guideline charts.

Here is a brief summary of my and Sergey’s actual stated motivations:

1. Cutters wishing to have their diamonond’s blessed by both AGS and GIA are now cutting to the intersection of the GIA charts and the current outdated AGS guideline charts. This intersection is unnecessarily restrictive as we see in examples like P41cr35t56, which Peter has informed me is an AGS Ideal 0, while the charts give it an AGS 2.

2. Sergey answers the question: What is the agenda?
This is the agenda. It is to get the official answer from AGS whether the following are AGS Ideal 0:
6 mm 80 LG P41 Cr35 T57
1) Girdle( In bezel) 3% Star 50%
2) Girdle( In bezel) 3.5% Star 50%
3) Girdle( In bezel) 3% Star 55%
4) Girdle( In bezel) 3.5% Star 55%
If so how did the same diamond receive an AGS 3 in the AGS CHARTS?
Sergey Sivovolenko

3. In my writing I have endeavored to fairly and accurately represent the AGS range of Ideal 0. Now that AGS has informed us that this range has increased from the initial range represented in the charts, it seems in their interest to clarify this new range of Ideal 0 by updating those charts. Then the cutters could more accurately work with the true AGS extent of the Ideal 0 proportions.

I believe, like Paul Slegers stated, that “AGS-0 is only the beginning of the story, not the end.” I believe, as he also stated, “it is important to understand them (the AGS grades).”

Michael Cowing

 

[adamasgem]

Date: 2/20/2007 4:48:38 PM
Author: JohnQuixote

A word or two about the AGS cutting guideline charts: These are “guidelines” for manufacture and the charts were published exactly as compiled from perfectly formed virtual stones.In fact, only proportions sets that had absolutely no deductions of any kind were published as 0s. For instance, if the virtual stone received a deduction of 0.01 for brightness and a deduction of 0.01 for dispersion, it shows up on the guideline chart as a potential cut grade of 2.The lab understands that this is erring on the strict side, and may be seen as ‘unfair’ to some proportions sets.This is why, from day one, the AGS has told us again and again that the boundaries are ‘fuzzy’.

The lab extensively studied actual stones to see how accurately cutters could cut. Based on those studies, they set the amount of ‘fuzziness’ for the actual grading system. So…an actual stone may get a deduction of 0.1 for brightness and 0.3 for dispersion for a total of 0.4 and that stone will still get a 0 in light performance. The performance grade is rounded up at 0.5’s. So, 0.5 becomes a 1, 1.5 becomes a 2 etc. On the other hand, you can have a stone that sits in the ‘heart’ of 0 on the guideline proportions charts and because of a cutting problem (out of roundness, deleterious digging or painting, etc.) it could get a contrast deduction of 0.3 and a leakage deduction of 0.21 and then it would receive a 1 in light performance.

.

To the whiners out there, John Pollard, near the beginning of this thread, correctly described the AGS cutting guidelines charts. They are what they are. Regardless of what some whiners want to make of them.

When you start getting deductions, EVEN WITH PERFECT SYMMETRY, that may tell you you are on the edge of a cliff, and the gradient for deductions is most probably steeper at these borders.

SINCE NO STONE has absolutely perfect symmetry, more deductions will logically apply, JUST as deductions would start applying to a stone smack dab in the center of the AGS 0 guidelines.

The AGS 0 is not a parametrically based system, like the GIA, where a SUBJECTIVE EX symmetry, MAY still rate substantial AGS deductions.

The whole process is highly non linear, and while SOME would like to make more of what the AGS GUIDELINES are, the conservative charts serve the cutters well. They are what they are, and they have been adequately defined from the beginning.

Perhaps the whiners out there should do their homework themselves..

 

[michaelgem]

Hi John,

Re: I just tried to share an explanation of “why” the guides are conservative the way I understand it from experts I respect at the lab. If you hope to see the official charts updated maybe your reasoning and request could be made to AGS (?)

The explanation you shared is the current AGS position on the grading guideline charts.

To avoid misinterpretation and better serve the cutters, AGS would be wise to update these charts with the new cut criteria, which we were told is slightly more inclusive for the AGS Ideal 0.

Because the charts are for symmetric diamonds the warning should be made that the charts represent the best grade possible for these idealized diamonds, and actual diamonds may be further downgraded. (A diamond with less than perfect symmetry would never get a higher grade, would it? )

So, we have the one resolved instance where the charts say the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. Peter, using the current AGS-PGS software, says that it is an AGS Ideal 0.

I did contact Peter as you suggested. He said that he had seen my posts. While Peter did not rule out updating the charts, he is heavily involved right now in pursuits AGS sees as higher priority. Also, anything of this nature would have to be approved up the AGS line of management .

Ideal regards,

Michael

 

[adamasgem]

Date: 2/26/2007 1:03:24 PM
Author: michaelgem


So, we have the one resolved instance where the charts say the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. Peter, using the current AGS-PGS software, says that it is an AGS Ideal 0.

You either don''t listen, or CAN''t read....

The GUIDELINE CHART EXPLANATION IS PRETTY CLEAR,
but obviously not for whiners.

 

[Serg]

Date: 2/26/2007 3:06:45 PM
Author: adamasgem

Date: 2/26/2007 1:03:24 PM
Author: michaelgem



So, we have the one resolved instance where the charts say the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. Peter, using the current AGS-PGS software, says that it is an AGS Ideal 0.

You either don''t listen, or CAN''t read....

The GUIDELINE CHART EXPLANATION IS PRETTY CLEAR,
but obviously not for whiners.

Marty,
I need try start listen other peoples, It is more hard work than speak and write.
It is boringly discuss with you if you do not like listen

 

[WinkHPD]

Date: 2/26/2007 3:06:45 PM
Author: adamasgem

Date: 2/26/2007 1:03:24 PM
Author: michaelgem



So, we have the one resolved instance where the charts say the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. Peter, using the current AGS-PGS software, says that it is an AGS Ideal 0.

You either don''t listen, or CAN''t read....

The GUIDELINE CHART EXPLANATION IS PRETTY CLEAR,
but obviously not for whiners.

Why must you be so abusive? Your comment is not at all conducive to good conversation or salient to the point being discussed. You remind me of the tourists I used to see when I lived in Rio de Janeiro many years ago. When a native who did not speak English was unable to answer a question the question was repeated more loudly until the question asker was literally yelling. It never got them a good answer...

I respect your right to disagree with Michael and any one else you want to, but question the need for your abusive tone of voice.

Wink

 

[adamasgem]

Date: 2/26/2007 5:06:51 PM
Author: Wink

Date: 2/26/2007 3:06:45 PM
Author: adamasgem

Date: 2/26/2007 1:03:24 PM
Author: michaelgem




So, we have the one resolved instance where the charts say the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. Peter, using the current AGS-PGS software, says that it is an AGS Ideal 0.

You either don''t listen, or CAN''t read....

The GUIDELINE CHART EXPLANATION IS PRETTY CLEAR,
but obviously not for whiners.

Why must you be so abusive? Your comment is not at all conducive to good conversation or salient to the point being discussed. You remind me of the tourists I used to see when I lived in Rio de Janeiro many years ago. When a native who did not speak English was unable to answer a question the question was repeated more loudly until the question asker was literally yelling. It never got them a good answer...

I respect your right to disagree with Michael and any one else you want to, but question the need for your abusive tone of voice.

Wink

Duely Noted Wink... I stand spanked..

However, the highlighted phrase above I believe is a complete misrepresentation of the AGS chart''s explanation.

The charts were issued for NO deductions at all, zero threshold tolerance. THEY ARE NOT GRADING CHARTS.

When Peter is quoted that "it" would receive an AGS 0 from PGS software, he may or may not be saying that there were zero deductions currently, only that the deductions, however large or small, did not meet the threshold for excluding it from a 0.

Besides, this thread discussed a 57% table, not a 56% table

 

[RockDoc]

I think that not everyone is understanding Marty''s " main " reason for disagreeing so vehemently.

To quote:

So, we have the one resolved instance where the charts say the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. Peter, using the current AGS-PGS software, says that it is an AGS Ideal 0.

It is " it is at best " a particular grade that I believe that he takes issue with. To that extent Marty is correct in his statements.

The charts were GUIDELINES, and some might get cut gradings from AGS 2 to AGS 0 cut grades. These gradings are a "prediction" based on the limiations between each of the grades, which was done SO CUTTERS WOULD HAVE AN IDEA of how, if they cut a stone to those particular angles/percentages would grade. As one departs from the symmetricaly "perfect stone" for each grading, the probability of getting a lower grade increases.

The charts being written about don''t include the results of the ray tracing results that is affected by the individual scan, and is representative only of a virtual, perfectly symmetrical stone.

Visual symmetry and optical symmetry included in the analysis of the PGS software isn''t included in the GUIDELINES which PREDICT GRADE. The prediction is approximate, and most cutters that are using the AGS charts to fashion their stones I am sure are very aware of the limitations that the charts impose as shown.

So some cutters may be williing to "roll the dice" more than other by cutting closer to the borders for each cut grade. Sometimes rolling the dice is a winner and sometime it isn''t.

I think it has been shown with updated cut grade system the narrow previously percentage are much broader now, also resulting in not being to conclusively a cut grade from chart.

So as a final question one needs to ask : " Did AGS ever state that these would be the "best gradings'' by viture of use of the charts.?" The answer is a resounding NO, as the charts were GUIDELINES for cutters.


Rockdoc

 

[Garry H (Cut Nut)]

And Michael what of creativity?

What if a creative cutter can find a way to paint or dig a diamond that is right on a border for the perfect virtual stone - and it can be enhanced according to AGS''s PGS software?

But really I think this thread has gone on too long and has (as Wink pointed out) become a he said, she said slanging match.

 

[michaelgem]

Date: 2/26/2007 7:28:30 PM
Author: RockDoc

As one departs from the symmetricaly ''perfect stone'' for each grading, the probability of getting a lower grade increases.

The charts being written about don''t include the results of the ray tracing results that is affected by the individual scan, and is representative only of a virtual, perfectly symmetrical stone.

So some cutters may be williing to ''roll the dice'' more than other by cutting closer to the borders for each cut grade. Sometimes rolling the dice is a winner and sometime it isn''t. As you imply this roll of the dice can only break even or loose relative to the charts grade of a virtual, perfectly symmetrical stone.

So as a final question one needs to ask : '' Did AGS ever state that these would be the ''best gradings'' by viture of use of the charts.?'' The answer is a resounding NO, as the charts were GUIDELINES for cutters.


Rockdoc

Bill,

Re: So, we have the one resolved (by Peter) instance where the charts say the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. Peter, using the current AGS-PGS software, says that it is an AGS Ideal 0.

You''re correct. AGS has not said that the Guideline charts indicate the grade for the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. However, it should be evident to you from your own logic and the following:

1. Charts say a perfect symmetry 6mm diamond, cut with P41CR35T56 = AGS 2.
2. Actual diamonds seldom have mathematically perfect symmetry, so they will either score the same or lower. That is unless you believe that cutting a less perfect diamond is rewarded with a higher grade by the AGS-PGS software. Most of us (including you I think) believe that a less symmetric diamond leads to deductions, not a better grade.
3. So the current guideline charts mislead us to believe that we will at best get an AGS 2 if we cut to P41CR35T56.
4. But Peter, using AGS-PGS software, finds that the perfect symmetry P41CR35T56 is an AGS Ideal 0.
Michael

 

[michaelgem]

Date: 2/26/2007 8:44:19 PM
Author: Garry H (Cut Nut)
And Michael what of creativity?

What if a creative cutter can find a way to paint or dig a diamond that is right on a border for the perfect virtual stone - and it can be enhanced according to AGS''s PGS software? Even if the cutter had the PGS software, how do you propose he go about figuring out this creative enhancement?

Garry,

Are you raising a herd of ''red herrings'' down under?

You know that Peter has said that painting and digging lead to deductions and certainly not to a better grade.

How is a cutter, working with the current guideline charts supposed to exercise creativity? He doesn''t even know for the best case scenario the extent of Ideal 0 .

Michael Cowing

 

[strmrdr]

Date: 2/26/2007 9:14:56 PM
Author: michaelgem

You know that Peter has said that painting and digging lead to deductions and certainly not to a better grade.

Michael Cowing

Do you know if that is in writing someplace because id be interested in reading it?
The official position iv been getting from pretty much everyone is that they are neutral on it except where it affects the performance enough to bump/dump it a grade.

Therefore it might be possible for it to move a stone up.

With the sarin scanners they were using it was likely not being picked up accurately anyway except recently with the software upgrade and that hasnt been proven yet to have helped.

I pretty much agree with it always being a down grade beyond a very slight amount but the grading reports that Iv seen says that AGS does not agree with that position.

 

[strmrdr]

complaint mode on:

Guys I think its awesome that AGS keeps a channel open with you/us but all this Peter says stuff especially out of context and 3rd hand gets confusing as all get out for people trying to follow this and figure out just what is going on.
We have no clue what the context was and in different context the answer can be 100% opposite and it gets extremely frustrating when we get Peter saids that disagree with each other because we dont have the context of the message to base understanding on.

complaint mode off:

 

[adamasgem]

Date: 2/26/2007 9:14:56 PM
Author: michaelgem

Date: 2/26/2007 8:44:19 PM
Author: Garry H (Cut Nut)
And Michael what of creativity?

What if a creative cutter can find a way to paint or dig a diamond that is right on a border for the perfect virtual stone - and it can be enhanced according to AGS''s PGS software? Even if the cutter had the PGS software, how do you propose he go about figuring out this creative enhancement? I guess you wouldn''t know the first way to approach the non linear problem, do you, if you have to ask the question??????

Garry,

Are you raising a herd of ''red herrings'' down under?

You know that Peter has said that painting and digging lead to deductions and certainly not to a better grade.Well, Peter likes painting enough to wear an EightStar, so I guess there might be something positive about painting.

How is a cutter, working with the current guideline charts supposed to exercise creativity? He doesn''t even know for the best case scenario the extent of Ideal 0 .No, Michael, the cutter can interpret the charts as saying he is on the edge of a hill, and it might be the Grand Canyon. And it edge of the cliff maybe somewhere within the Table Size, Crown angle, Pavilion angle quantization range of the charts Perhaps you''ve never interpreted a typographical map. But I guess you want the charts in finer scale, now, don''t you? Every thousandth of a degree OK with you?

Michael Cowing

 

[JohnQuixote]

Date: 2/26/2007 9:14:56 PM
Author: michaelgem

You know that Peter has said that painting and digging lead to deductions and certainly not to a better grade.

It''s strange that you say this Michael. Digging has limited positive applications but painting can be neutral, subtractive or additive. It depends on how much and where.

Guys, as sophisticated as we are it''s a chuckle that we still say "painting" by itself and expect it to imply what we each see in our individual minds...a good monster...a bad monster...a monster waving a Switzerland flag... The word "painting" (and his usually-naughty brother digging) cannot imply + or - by itself.

 

[JohnQuixote]

Date: 2/26/2007 9:34:51 PM
Author: strmrdr

Date: 2/26/2007 9:14:56 PM
Author: michaelgem

You know that Peter has said that painting and digging lead to deductions and certainly not to a better grade.

Michael Cowing

Do you know if that is in writing someplace because id be interested in reading it?
The official position iv been getting from pretty much everyone is that they are neutral on it except where it affects the performance enough to bump/dump it a grade.

Therefore it might be possible for it to move a stone up.

It certainly is. As I said above, it depends on the particulars.

All things being equal, painting shallow stones is no bueno. Painting near-Tolk can broaden scintillation in an appealing way if done in moderation (and only on the crown) or can darken the stone if done too far and/or on the pavilion. Painting deep stones can improve the appearance.


Example: 58, 61.2, 41.2, 35.4 no painting.

 

[JohnQuixote]

And...

Same diamond: 58, 61.2, 41.2, 35.4 but with 4 degrees average crown painting & average pavilion painting.

(And look!...the sneeky cutter saved 0.81 instead of 0.80)

 

[JohnQuixote]

Date: 2/26/2007 9:50:29 PM
Author: strmrdr
complaint mode on:

Guys I think its awesome that AGS keeps a channel open with you/us but all this Peter says stuff especially out of context and 3rd hand gets confusing as all get out for people trying to follow this and figure out just what is going on.
We have no clue what the context was and in different context the answer can be 100% opposite and it gets extremely frustrating when we get Peter saids that disagree with each other because we dont have the context of the message to base understanding on.

complaint mode off:

Agree 100%. We're furiously rowing just one side of the boat. People on the shore are pointing and laughing. I let go of the oar after p2 but got sucked back in tonight.

 

[michaelgem]

Date: 2/26/2007 11:28:35 PM
Author: JohnQuixote

Date: 2/26/2007 9:14:56 PM
Author: michaelgem

You know that Peter has said that painting and digging lead to deductions and certainly not to a better grade.

It's strange that you say this Michael. Digging has limited positive applications but painting can be neutral, subtractive or additive. It depends on how much and where.

John,

Strmrdr is complaining that you and I and others are quoting Peter and he worries we may be misrepresenting him. I often check with Peter to make sure I accurately represent what he tells me.

With regard to painting I have in prior threads accurately relayed his statement that painting leads to deductions from AGS's dispersion metric. In your case the relatively small amount is not enough to drop you out of the Ideal 0, as you know. He has not allowed that painting could lead to a better grade.

I happen to agree with you that the type of painting you do in your New Line diamond can have positive benefits to diamond beauty depending upon the viewing and illumination circumstances.

I wonder why I get lots of negative response to some side issue like this one, and little reasoned response addressing Sergey and my main arguement for updating the misrepresentations of the current Ideal 0 range in the now obsolete cut grade estimation/guidline charts?

Sergey and I have gone to great lengths to make a good clear case for straightening out those charts for the cutters and for clarity.

Michael Cowing

 

[strmrdr]

Date: 2/27/2007 12:03:51 AM
Author: michaelgem

John,

Strmrdr is complaining that you and I and others are quoting Peter and he worries we may be misrepresenting him. I often check with Peter to make sure I accurately represent what he tells me.

With regard to painting I have in prior threads accurately relayed his statement that painting leads to deductions from AGS''s dispersion metric.

Michael Cowing

"misrepresenting him" is too strong a way of putting it. There isn''t malice in it most of the time.

You going to hate me,,,,,,
But,
sorry the above in BOLD that is exactly what I''m talking about.
That is not what you said above, the context of dispersion was missing.
Now that the context is there we can discuss it in line with what AGS''s thinking may be.
Which brings me to this:

In theory you can balance that hit against the increases in other areas and get a higher grade with some combos.
There have been diamonds with way more painting than I like that got AGS0 so there is a lot of room to play with it.

See the difference a little context makes?

 

[Serg]

Date: 2/26/2007 7:28:30 PM
Author: RockDoc

I think that not everyone is understanding Marty's ' main ' reason for disagreeing so vehemently.

To quote:

So, we have the one resolved instance where the charts say the perfect symmetry 6mm diamond, cut with P41CR35T56, is at best an AGS 2. Peter, using the current AGS-PGS software, says that it is an AGS Ideal 0.

It is ' it is at best ' a particular grade that I believe that he takes issue with. To that extent Marty is correct in his statements.

The charts were GUIDELINES, and some might get cut gradings from AGS 2 to AGS 0 cut grades. These gradings are a 'prediction' based on the limiations between each of the grades, which was done SO CUTTERS WOULD HAVE AN IDEA of how, if they cut a stone to those particular angles/percentages would grade. As one departs from the symmetricaly 'perfect stone' for each grading, the probability of getting a lower grade increases.

The charts being written about don't include the results of the ray tracing results that is affected by the individual scan, and is representative only of a virtual, perfectly symmetrical stone.

Visual symmetry and optical symmetry included in the analysis of the PGS software isn't included in the GUIDELINES which PREDICT GRADE. The prediction is approximate, and most cutters that are using the AGS charts to fashion their stones I am sure are very aware of the limitations that the charts impose as shown.

So some cutters may be williing to 'roll the dice' more than other by cutting closer to the borders for each cut grade. Sometimes rolling the dice is a winner and sometime it isn't.

I think it has been shown with updated cut grade system the narrow previously percentage are much broader now, also resulting in not being to conclusively a cut grade from chart.

So as a final question one needs to ask : ' Did AGS ever state that these would be the 'best gradings' by viture of use of the charts.?' The answer is a resounding NO, as the charts were GUIDELINES for cutters.


Rockdoc

Bill, I will try give more full explanation too.
Yes, LAB can publish two type charts
1) First type: For ideal 3D symmetry diamonds
2) Second type: Guideline for cutters with accounting accuracy of cutting.

Second type charts should satisfy next conditions at least:
a) Should be mention tolerance for cutting. Manufactures have quit different level technology. For what type tolerance (manufacture) did AGS publish guideline charts?
b) For each set of parameters grade( value of chart) in second type chart should be same or worse than grade in first type chart

I guideline charts do not satisfy to first condition, it are very misleading charts
IF guideline charts do not satisfy to second condition, it are wrong charts.

AGS guideline charts are wrong and misleading in same time.

I am understanding political answer from AGS( It is just for cutters, we just want do good service). But I can not understand and accept Marty position who do not like see such evident technical problem with AGS guideline charts

I do not like be pro AGS or pro GIA. I try keeping my eyes and minding open.
Each person and company can do mistake, it is normal. Important How are fixing your mistake.

 

[Serg]

Date: 2/26/2007 11:28:35 PM
Author: JohnQuixote

Date: 2/26/2007 9:14:56 PM
Author: michaelgem

You know that Peter has said that painting and digging lead to deductions and certainly not to a better grade.

It''s strange that you say this Michael. Digging has limited positive applications but painting can be neutral, subtractive or additive. It depends on how much and where.

Guys, as sophisticated as we are it''s a chuckle that we still say ''painting'' by itself and expect it to imply what we each see in our individual minds...a good monster...a bad monster...a monster waving a Switzerland flag... The word ''painting'' (and his usually-naughty brother digging) cannot imply + or - by itself.

John,

From one side:AGS grade system is deduction system. Nothing can not improve grade, even right painting.
from other side: influence of painting had been included to optical AGS grade of course( like anything in 3d model) From with side painting can improve AGS grade of course
Both statements formally are correct

 

[michaelgem]

Date: 2/27/2007 1:12:41 AM
Author: strmrdr

Date: 2/27/2007 12:03:51 AM
Author: michaelgem

With regard to painting I have in prior threads accurately relayed his statement that painting leads to deductions from AGS''s dispersion metric.

Michael Cowing

''misrepresenting him'' is too strong a way of putting it. There isn''t malice in it most of the time.

You going to hate me,,,,,,
But,
sorry the above in BOLD that is exactly what I''m talking about.
That is not what you said above, the context of dispersion was missing.
Now that the context is there we can discuss it in line with what AGS''s thinking may be.
Which brings me to this:

In theory you can balance that hit against the increases in other areas and get a higher grade with some combos.
There have been diamonds with way more painting than I like that got AGS0 so there is a lot of room to play with it.

See the difference a little context makes?

Strmrdr,

Your point is well taken. For instance, had I added that in addition to "painting leads to deductions from AGS''s dispersion metric" that Peter also said it did not appear to impact the ASET metric, there would be less room for speculation that painting could improve the grade in the AGS system.

Relative to the grade of a normally indexed, virtual diamond from the chart, I gather from what John says that the grade may be kept the same by such creativity, but as I explained to Bill, real life variations from the idealized diamond of the charts results in deductions, not an increase in grade.

The problem is that carrying along all the context with every point makes for a long post that few read and that for most obscures the main message. For instance, if each time I mention the grade estimation/guideline chart''s diamonds, I include mathematicallly symmetrical, P41cr35t56, 80% lower half, 55% star length, 3.5% girdle at the mains, the post quickly gets long. If I don''t someone assumes I am speaking of a wider class of diamonds.

So the amount of context to include to clarify each thought is a trade off between trying to be brief and to the point, but still keep to a minimum the inevitable misinterpretation.

Michael