Letter to the Editor of the Australian Gemmologist

[strmrdr]

As far as the labs telling the cutters what to do there are other labs out there if they don''t like it don''t use them and we the people can decide which lab we are going to trust and their sales will either rise or fall.
I like the fact that AGS is not rubber stamping what the cutters want to cut which is what GIA did by having the trade viewers set the grade.

 

[adamasgem]

Date: 3/8/2007 10:34:48 AM
Author: michaelgem

Until the AGS issues new charts reflecting the current PGS range of Ideal 0, your cut groups chart work is the best reference as to how that range has grown from its original extent shown in the guideline charts. I enclose a superposition of the cut groups charts to examine how that range has grown.

The yellow is the Ideal 0 range of the current guideline charts, and the blue is the Ideal 0 range the cut group obtained from the PGS software. The first thing I notice, besides the large increase in Ideal 0, is that the growth is not symmetrical.

The current guideline charts don’t seem to be the best aid to the cutters. Notice that on the shallow/shallow side the guidelines have the cutter on the edge of falling out of the zero, while there is greater room for error in the steep/deep direction. The cutter is also not seeing in the guideline charts the large area of zero’s in the shallow/deep direction.

If any of this analysis is wrong or misleading I anticipate that AGS will provide clarification and correction.

Michael Cowing

For the 100''th time, Mr Continuously Misleading (interesting juxtaposition of your initials MC and CM) , the AGS GUIDELINE CHARTS are NOT GRADING Charts, and were never intended as such.

Or maybe a lack of comprehension?

 

[adamasgem]

Date: 3/8/2007 12:04:17 PM
Author: Serg
.

Serg.. I don''t understand what you mean by PGS with three rank filter...

You appear to be summing deductions for the symmetrical case at 57 table size for ideal polish and perfect symmetry
but I don''t know if you are only including light performance or not

I take it that the commas inside the boxes are meant as decimal points(German convention)?

If you have all the baseline deductions for the symmetrical case, including tilt and weight, you now have to figure out the PGS sensitivities at each point ( which will be different at each point) to assymetries and then apply those to the baseline symmetrical deduction..

It is obvious to me that in a point which has a baseline symmetrical deduction of, lets say 0.4, then I would assume that the probability of assymetries would bringing the total true deducton over the integer rounding threshold to be much higher than the four points you have as 0,0 (0.0) in your chart.

What I don''t know, is what are the statistics of the additional deductions (mean and standard deviation from symmetrical) arising from asymmetries to the level allowed by GIA in rating a stone VG for symmetry, or those within the AGS 0 symmetry class..

And I don''t know how to do that, other than extensive simulations from actual scans which recieved GIA EX for symmetry which may include AGS 0 and 1 symmetry, but I am not sure on that.

These are the last definitions I could dig up..

Polish(and I believe similar nomenclature applies to symmetry) according to GIA

EX: ranges from having no polish features to a few minute features that can be located with difficulty at 10X.
VG: a few minor polish feature when viewed at 10X
G: areas of noticable polish features when viewed at 10X. The luster of the diamond is not impaired when viewed with the unaided eye"
F: areas of obvious polish features that are readily seen at 10X. The luster of the diamond is affected when viewed with the unaided eye"
P: prominent heavy polish features hamper the life of the diamond at 10X. The luster of the diamond is strongly influenced when viewed with the unaided eye"
Pol/Sym AGS
0 "Extremely difficult to locate under 10X"
1 "Very difficult to locate under 10X"
2 "Difficult to locate under 10X"
3 "Relatively easy to see under 10X, not visible to unaided eye"
4 "Easy to see under 10X, extremely difficult to see with the unaided eye"
5 "Very easy to see under 10X, very difficult to see with unaided eye"
6 "Obvious to see under 10X, difficult to see with unaided eye"
7 "Relatively easy to see with unaided eye"
8 "Easy to see with unaided eye"
9 "Obvious to the unaided eye"
10 "Obvious to the unaided eye"

 

[adamasgem]

Date: 3/8/2007 11:57:59 AM
Author: Yuri

Date: 3/8/2007 2:19:54 AM
Author: adamasgem

Well Sergey, the statistics that I posted showing that only about 14% of GIA graded RBC''s got an EX/EX for polish and symmetry tells me, as far away from the cutters you may think I am, that they, the cutters, have a lot to learn. Hope you can help them with the basics..

Marty, cutters work with various types of rough diamonds. Rough classification has more than 18 000 positions and is far more complicated than the current classification of polished diamonds.
Yuri.. Yup, I have seen the ream of paper deliniating the 1000''s of DeBeers rough classifications

1. Out of all incoming rough diamonds cutters preselect stones that intended to be polished to Ideal, Ex/Ex/Ex, AGS000. it can be 15% and depends on quality of rough.
I would think that cutter''s skill has a lot to do with it also..

The similar idea works for fancy cuts: stones are preselected because of their shape and inclusions. At the last GIA symposium we saw a 100 ct D IF emerald cut that was so flat that every observer could see the backgroung through it. I guess that if a curret choose to polish an excellent rbc, he will probably get 30 - 40ct but not 100. Do you think this stone needs to be recut? I don''t know, that is an econimic decision.


2. Is seems that both GIA and AGS new grading systems helps to sell 14% of round diamonds and makes sales of all other rounds and all fancy cuts more problematic. I see the new GIA system as attempt to make it easier as the paradigms are different

But it does not mean that all other diamonds are worse. In the same manner, If you buy a car, you can buy a Yugo or a Rolls Royce.. But one may be optimal (by whatever definition you chose to use) and one may not, if you want utilitarian only, then you get the Yugo, or maybe a low end Chevy.

The problem that there are many variations of rough and cutters know this very well. They do their good work to provide many types of diamond to many types of consumers who, in turn, have variuos tastes, opinions and preferences. Yup

And now what? The foremost authorties who never cut diamonds came to the scene because they are going to have more money by issuing papers and say that they have the best cut standard in the world now and all diamonds sould be cut equal like balls for a ball-bearing. I believe that some are saying that ball bearings with flat spots will roll as well as ones that are perfect spheres.

I will be glad to hear your comment on this. I think the two major labs we are talking about have differnent paradigms about what they now consider the "best", with GIA pandering to the trade with a continuing loosening of definitions and "standards".

In my opinion, GIA was initially trying to go along the right track, and then they backtracked to satisfy the mass merchandisers, especially with the "taste test" approach.

The four paradigms we know a little about, namely GIA, MSU (Octonus), HCA and AGS are different, and yet they overlap in their results some areas, and disagree in others.

Maybe the best thing for consumers is to see where they ALL agree, and if so inclined, buy that category of stone.

 

[Serg]

Marty,
Do you have time for work?

 

[adamasgem]

Date: 3/8/2007 5:47:52 PM
Author: Serg
Marty,
Do you have time for work?

Not lately, with trying to correct, for the consumer, Continously Misleading assumptions..

I do enjoy a technical exchange now and then..

 

[michaelgem]

Has anyone noticed how excessively NOISY it has gotten on PriceScope? It is like trying to be heard over the noise made by a herd of stampeding buffalo.

Re:
Michael did not say whether the GIA system is better or worse than AGS.
He said that we can use charts and parametrical (ideal models) for comparing RESULTS from the GIA and AGS cut grading systems.
He said it because Marty wrote that such a method is not correct.
If course we can do it. We are doing it. And this method is correct.
Sergey Sivovolenko

Thank you, Sergey,

Maybe just you and I are on the same page concerning the parametric/nonparametric discussion.

Doesn’t anyone except Sergey and I understand and want to address the reasoning we have presented for consideration by AGS and PriceScope?

Is there no interest in learning more about what AGS currently considers Ideal in round brilliant diamond cutting?

Is there no interest by the cutters in knowing that the current guideline charts have little to no leeway in the shallow-shallow direction, but plenty in the steep-deep?

Is there no interest by the cutters in knowing that there is lots of room to get a zero in the shallow-deep direction that is not shown in the guideline charts? That knowledge alone allows for a greater yield from typical octahedral rough. Doesn’t anyone think cutters care to know about this?

Is no one interested in discussing what he or she thinks of the AGS-PGS greater range of Ideal 0? Does anyone think the original tighter range is better and why?

These are considerations that interest me, not someone’s opinion that one system sucks and the other walks on water. Especially when neither is true.

Michael Cowing

 

[strmrdr]

Date: 3/8/2007 6:24:01 PM
Author: michaelgem

Doesn’t anyone except Sergey and I understand and want to address the reasoning we have presented for consideration by AGS and PriceScope?

I understand it 100% just dont agree that it will mean anything if they do update the charts.
They still can not be used to set a grade.

 

[Serg]

Date: 3/8/2007 6:07:45 PM
Author: adamasgem

Date: 3/8/2007 5:47:52 PM
Author: Serg
Marty,
Do you have time for work?

Not lately, with trying to correct, for the consumer, Continously Misleading assumptions..

I do enjoy a technical exchange now and then..

correct to consumer misleading?

may be you want just say defense AGS brand?
It is not same.

And what is about cutters misleading?

Two options:
1) I and Michael are wrong. In such case how many cutters and consumers could UNDERSTAND what are AGS charts mean?
2) I and Michael are right. In such case How many cutters and consumers are Misleading now?

Sorry, Marty I do not see what you even try correct misleading or misunderstanding.

Strmrdr,

We do not try use charts for grade! We do not even try use PGS for grade.

We are speaking about Guidelines( AGS and GIA). Between GRADE SYSTEM and GUIDELINES should be strong correlation. It is MAP . It is very strange see different MAPs and hear: do not use AGS MAP.
BTW. Usually if some misunderstanding ( or just not enough understanding) about AGS cut grade system happened on PS, you can see very FAST and HELPFUL reaction from Peter Y.
Nothing from Peter is now on PS.
Just Marty try add chaos.

 

[strmrdr]

this thread has gotten near impossible to follow....

Serg,
Newer AGS charts as guidelines for cutters we are on the same page there its a good thing.
Its when the discussion turns to using them for anything beyond that is where I disagree.

And
Honestly based on my understanding of the AGS grading system I don''t see where charts will ever be very accurate at predicting the grade.

What would be nice is a computer program where a cutter can enter say the available crown and pavilion height of the bruted rough and get the best combo that will get the AGS0 grade that fits inside that.
But that is even more so telling the cutters how to cut stones so dunno.
But it would be a lot better than charts.

 

[strmrdr]

Date: 3/8/2007 6:24:01 PM
Author: michaelgem

Is no one interested in discussing what he or she thinks of the AGS-PGS greater range of Ideal 0? Does anyone think the original tighter range is better and why?

I think the original was too wide and the newer too wide too but if I was the one deciding the grade all the cutters would be out to lynch me because they would have little to no wiggle room and charges of cookie cutter diamonds would fly!
Every diamond would have to be very tight and eye perfect hearts with a very narrow range of angles lgf% with less than .2 degrees painting and 0 degrees digging allowed.
It would also be seperated into 2 classes:
strmRing <---- this class would make everyone mad.
strmPendant-EarRing <--- this class would make Garry very happy

 

[Serg]

Date: 3/9/2007 3:17:54 AM
Author: strmrdr
this thread has gotten near impossible to follow....

Serg,
Newer AGS charts as guidelines for cutters we are on the same page there its a good thing.
Its when the discussion turns to using them for anything beyond that is where I disagree.

And
Honestly based on my understanding of the AGS grading system I don''t see where charts will ever be very accurate at predicting the grade.

What would be nice is a computer program where a cutter can enter say the available crown and pavilion height of the bruted rough and get the best combo that will get the AGS0 grade that fits inside that.
But that is even more so telling the cutters how to cut stones so dunno.
But it would be a lot better than charts.

re:What would be nice is a computer program where a cutter can enter say the available crown and pavilion height of the bruted rough and get the best combo that will get the AGS0 grade that fits inside that.
But that is even more so telling the cutters how to cut stones so dunno.
But it would be a lot better than charts.

Strmrdr,
Take such software, check different combination crown and pavilion angles, print it. Again you will receive chart.
Form of presentation is not important . Charts is just more effective for human analysis. Human analysis is very important for developing strategy of cutters/ It was great mistake from GIA-SARIN-OGI delay publish charts. AGS won a lot of just from it

 

[diagem]

News:

http://www.idexonline.com/portal_FullNews.asp?SID=&id=27149

 

[michaelgem]

I learn more from Sergey when I take the time to reword his thinking, as I would say it. Posting it is my way of seconding my perception of his reasoning.

Correcting statements that are misleading to the consumer?

Maybe you should just say you want to defend the AGS brand?

It is not the same.

And what about misleading the cutters?

Two options:

1) I and Michael are wrong. If such is the case how many cutters and consumers could UNDERSTAND what the AGS charts mean?

2) I and Michael are right. In this case how many cutters and consumers are being mislead now?

Sorry, Marty I do not see that you even try to correct misleading or misunderstanding.

Strmrdr,

We do not try to use charts to grade! We do not even try to use PGS to grade.

We are speaking about Guidelines (The charts of both AGS and GIA are guidelines for both the cutters and consumers). Between a GRADE SYSTEM and GUIDELINES there should be a strong correlation. It is a MAP. It is very strange to see different MAPs and hear: do not use the AGS MAP.

BTW. Usually if there is some misunderstanding (or just not enough understanding) about the AGS cut grade system occurring on PS, you usually see a very FAST and HELPFUL reaction from Peter Y.

There is nothing from Peter now on PS.

Just Marty trying to add chaos.

Strmrdr,

Take software such as PGS, and check different combinations of crown and pavilion angles, print it. You will have created a chart.

The form of this presentation is not important. Charts are just more effective for human analysis. Human analysis is very important for developing the cutter’s strategy. It was a great mistake by GIA-SARIN-OGI when they delayed publishing GIA’s charts. AGS won a lot by publishing their charts first.

Sergey Sivovolenko seconded by Michael Cowing

 

[strmrdr]

ugh...
the crown and pavilion angles are not enough info to put on the charts.
spread, girdle, painting, tightness,lgf% and stars would also need to be included.
Every facet is taken into account within the limits the sarin scanner they are using.
Which is a whole nuther story and one bad thing about it that they aren''t using the best tech to generate the models.

 

[michaelgem]

Date: 3/9/2007 12:17:01 PM
Author: strmrdr
ugh...
the crown and pavilion angles are not enough info to put on the charts.
spread, girdle, painting, tightness,lgf% and stars would also need to be included.
Every facet is taken into account within the limits the sarin scanner they are using.
Which is a whole nuther story and one bad thing about it that they aren't using the best tech to generate the models.

Strm,

How many times have we pointed out the obvious, that the charts are idealized, normally indexed diamonds with the chart labled table size, star length and lgf%?

How many times have we acknowledged that real diamonds with less than perfect symmetry will score no better and most often worse. (This is for normal indexing. The exception John pointed out is the painted crown case.)

What did you not understand about:

Take software such as PGS, and check different combinations of crown and pavilion angles, print it. You will have created a chart.The form of this presentation is not important. Charts are just more effective for human analysis. Human analysis is very important for developing the cutter’s strategy.

Ask yourself, if I were a cutter working with a variety of rough and wanting the blessing of an AGS Ideal 0 for my diamonds, would I be better off knowing the current guideline range of zero (yellow) or the real PGS range (blue)?

Michael Cowing

 

[strmrdr]

Date: 3/9/2007 1:46:38 PM
Author: michaelgem

Date: 3/9/2007 12:17:01 PM
Author: strmrdr
ugh...
the crown and pavilion angles are not enough info to put on the charts.
spread, girdle, painting, tightness,lgf% and stars would also need to be included.
Every facet is taken into account within the limits the sarin scanner they are using.
Which is a whole nuther story and one bad thing about it that they aren''t using the best tech to generate the models.

Come on Strm,

How many times have we pointed out the obvious, that the charts are idealized, normally indexed diamonds with the chart labled table size, star length and lgf%?

How many times have we acknowledged that real diamonds with less than perfect symmetry will score no better and most often worse. (This is for normal indexing. The exception John pointed out is the painted crown case.)

What did you not understand about:

Take software such as PGS, and check different combinations of crown and pavilion angles, print it. You will have created a chart.The form of this presentation is not important. Charts are just more effective for human analysis. Human analysis is very important for developing the cutter’s strategy.

Michael Cowing

ok so we need a charts with lgf% in .5% increments, 1% for stars and .01% pavilion angle and .1% crown and .5% table, with 5 levels of girdle thickness and 10 levels of painting.
Which is how many 100 thousands of charts?

You will find combos that are one grade with 80% lgf% and another grade with 77% lgf% and a 3rd grade with 75% lgf% so they will all have to be represented.
Where 80% with painting is another grade yet again.
The range of combos is impossible to handle in chart form in a manageable manner and have any resemblance to accuracy

 

[adamasgem]

Date: 3/9/2007 2:03:47 PM
Author: strmrdr
ok so we need a charts with lgf% in .5% increments, 1% for stars and .01% pavilion angle and .1% crown and .5% table, with 5 levels of girdle thickness and 10 levels of painting.
Which is how many 100 thousands of charts?

You will find combos that are one grade with 80% lgf% and another grade with 77% lgf% and a 3rd grade with 75% lgf% so they will all have to be represented.
Where 80% with painting is another grade yet again.
The range of combos is impossible to handle in chart form in a manageable manner and have any resemblance to accuracy

Storm.. You seem to be the only one around here that understands the problem and the potential for misuse or mis- interpretation of AGS Guideline charts vis-a-vie GIA Grading charts

But we would also have to factor in the asymmetries and give a probability of getting that "Grade", based on a symmetrical model as a function of the level of asymmetry.

 

[michaelgem]

I was in the process of toning myself down a little and adding some substance to my post, but you beat me to the punch.

Date: 3/9/2007 2:03:47 PM
Author: strmrdr
ok so we need a charts with lgf% in .5% increments, 1% for stars and .01% pavilion angle and .1% crown and .5% table, with 5 levels of girdle thickness and 10 levels of painting.
Which is how many 100 thousands of charts?

You will find combos that are one grade with 80% lgf% and another grade with 77% lgf% and a 3rd grade with 75% lgf% so they will all have to be represented.
Where 80% with painting is another grade yet again.
The range of combos is impossible to handle in chart form in a manageable manner and have any resemblance to accuracy

How many times have we said that it is both necessary and sufficient to update the current missleading charts to reflect the current range of Ideal 0? Those charts, updated with the PGS software, would give the cutters a much better idea of how best to fashion the diamond to get an Ideal 0.

Ask yourself, if I were a cutter working with a variety of rough and wanting the blessing of an AGS Ideal 0 for my diamonds, would I be better off knowing the current guideline range of zero (yellow) or the real PGS range (blue)?

Michael Cowing

 

[strmrdr]

There is an error in my above post that I didnt catch and the edit time has expired.
"ok so we need a charts with lgf% in .5% increments, 1% for stars and .01% pavilion angle and .1% crown and .5% table, with 5 levels of girdle thickness and 10 levels of painting."

Should read..
"ok so we need a charts with lgf% in .5% increments, 1% for stars and .01 pavilion angle and .1 crown angle and .5% table, with 5 levels of girdle thickness and 10 levels of painting."

But the idea is the same either way.....

 

[strmrdr]

michaelgem,
The chart you posted will make my point very well with some help from Peter.
Have Peter run:
40.4 37.5 57 with 75% lgf 77% lgf% 80% and 85% lgf percentage and look at the grades.

and

41.8 31 57 with the same and look at the scores.

and

34.5 40.9 57 with the same and look at the scores.
.............
Then run the best scoring lgf% combo for each with 6 degrees crown painting and look at the score.

The scores will be all over the place I will bet $10 to your favorite charity over it.

 

[michaelgem]

Date: 3/9/2007 2:54:24 PM
Author: strmrdr
michaelgem,
The chart you posted will make my point very well with some help from Peter.
Have Peter run:
40.4 37.5 57 with 75% lgf 77% lgf% 80% and 85% lgf percentage and look at the grades.

and

41.8 31 57 with the same and look at the scores.

and

34.5 40.9 57 with the same and look at the scores.
.............
Then run the best scoring lgf% combo for each with 6 degrees crown painting and look at the score.

The scores will be all over the place I will bet $10 to your favorite charity over it.

Strm,

Your point is well taken.

If this type of detailed problem exists, having the PGS software will not be a solution for the cutters any more than having the updated guideline charts.

But at least the updated guideline charts would give the cutter a better idea of where to play in the Ideal 0 sandbox with less probability of falling out.

That is why I asked you to ask yourself, if I were a cutter working with a variety of rough and wanting the blessing of an AGS Ideal 0 for my diamonds, would I be better off knowing the current guideline range of zero (yellow) or the real PGS range (blue)?

I encourage everyone reading this as well as Strm to weigh in with your answer. Before you do, notice that there are two combinations said by the guideline charts to be zeros that no longer make the grade.

Everyone have a good weekend.


Michael Cowing

 

[michaelgem]

This just in from Peter Yantzer:

Jim Caudill has been kind enough to offer Sergey a copy of the AGS
Performance Grading Software with a hasp that will function for one
year.

AGS won''t be creating new guideline charts for the Round Brilliant. Our
existing guideline charts function perfectly well in aiding the cutting
industry in the manufacture of performance-based Ideal 0''s. And, the
diamond cutting industry has already modified their manufacturing
processes and learned how far from the published charts they can cut and
what grade they can expect to get from the AGS Lab.

With respect to the discussion about one of our published charts not
agreeing 100% with another set of our published charts, this is a very
minor issue. There are valid reasons why some of the guideline charts
changed slightly over time, principally because of the creation of the
.stl files and the amount of ''fuzziness'' or ''leeway'' built into the AGS
System to accommodate real-world cutting versus perfect, virtual stones.
Additionally, some of these charts are for 50% versus 55% star length,
80% lower girdle height versus 80% lower girdle length, 3% girdle versus
3.5% girdle which points out the consternation some people seem to be
having in comparing all of these charts to each other. The current post
is rife with confusion over which set of charts are being compared to
each other.

I agree with Marty Haske and strmrdr. The AGS system is enormously more
sophisticated than a two-dimensional chart. Creating more charts, in my
opinion, only serves to create expectations from someone viewing those
charts that may or may not be realistic. So, in this case, we''ll have
to agree to disagree.

Please feel free to post my comments.

Heartily,

Peter Yantzer, Director

American Gem Society Laboratories

 

[Serg]

Date: 3/9/2007 4:02:33 PM
Author: michaelgem

This just in from Peter Yantzer:

Jim Caudill has been kind enough to offer Sergey a copy of the AGS
Performance Grading Software with a hasp that will function for one
year.

BTW I hear it in first time. I do not know what is mean





AGS won't be creating new guideline charts for the Round Brilliant. Our
existing guideline charts function perfectly well in aiding the cutting
industry in the manufacture of performance-based Ideal 0's. And, the
diamond cutting industry has already modified their manufacturing
processes and learned how far from the published charts they can cut and
what grade they can expect to get from the AGS Lab.





With respect to the discussion about one of our published charts not
agreeing 100% with another set of our published charts, this is a very
minor issue.


Peter,
It is depends from point of view.
It is not minor issue even if AGS like think what it is minor issue


There are valid reasons why some of the guideline charts
changed slightly over time, principally because of the creation of the
.stl files and the amount of 'fuzziness' or 'leeway' built into the AGS
System to accommodate real-world cutting versus perfect, virtual stones.
Additionally, some of these charts are for 50% versus 55% star length,
80% lower girdle height versus 80% lower girdle length, 3% girdle versus
3.5% girdle which points out the consternation some people seem to be
having in comparing all of these charts to each other. The current post
is rife with confusion over which set of charts are being compared to
each other.

Peter,
You repeated here Marty posts.
I do not like repeat again why all these can not explain such big difference in AGS guidelines.
I am hope what you know real reason, I think I know now exactly what is real reason too.





I agree with Marty Haske and strmrdr. The AGS system is enormously more
sophisticated than a two-dimensional chart. Creating more charts, in my
opinion, only serves to create expectations from someone viewing those
charts that may or may not be realistic. So, in this case, we'll have
to agree to disagree.

Peter,
In any case thanks for answer. All is clear for me now.
I will continue discussion in other place with other interlocutors.

Best regards, Sergey

Please feel free to post my comments.

Heartily,

Peter Yantzer, Director

American Gem Society Laboratories

 

[michaelgem]

AGS won''t be creating new guideline charts for the Round Brilliant. Our
existing guideline charts function perfectly well in aiding the cutting
industry in the manufacture of performance-based Ideal 0''s. And, the
diamond cutting industry has already modified their manufacturing
processes and learned how far from the published charts they can cut and
what grade they can expect to get from the AGS Lab. Peter Yantzer

Peter,

On one hand you say:

“Our existing guideline charts function perfectly well in aiding the cutting
Industry in the manufacture of performance-based Ideal 0''s. “

Then with the next breath you say

AGS has taught the diamond cutting industry how far from the published charts they can cut.

This has just the opposite implication that the charts do not function perfectly well. AGS had to teach the industry the real story.

That does not sound like the existing guideline charts are functioning perfectly well.

It begs the question; why not tell us the real story, at least with respect to the easy to determine idealized case of the current guideline charts?

On one hand, AGS apparently has no problem with projecting to the world and its cutters and consumers an incorrect and misleading range of Ideal 0 in its guideline charts, while, on the other hand, it informs some manufacturers “how far from the published charts they can cut and what grade they can expect to get from the AGS Lab.”

All the effort and time Sergey and I have spent making the case for correcting obviously misleading guideline charts has worn me out, especially in light of you agreeing to disagree.

Oh well.

Michael Cowing

 

[adamasgem]

Michael: Are you going to post Peter''s email reply to you ?????????

 

[michaelgem]

Peter,

I have a call into you to resolve the evident problems you saw in my last post. Written communication is fraught with misintrepretation, as we have seen throughout this discussion thread. I do much better with verbal interaction.

You said "the diamond cutting industry has already modified their manufacturing
processes and learned how far from the published charts they can cut and
what grade they can expect to get from the AGS Lab."

I made a reasonable assumption that they learned how far from the published charts they can cut and
what grade they can expect to get from the AGS Lab" from the AGS.

That is why I said: "AGS has taught the diamond cutting industry how far from the published charts they can cut."

Did some one else teach them?

Confused regards,

Michael

 

[adamasgem]

Peter Yantzer said " And, the diamond cutting industry has already modified their manufacturing
processes and learned how far from the published charts they can cut and
what grade they can expect to get from the AGS Lab. "


Cowing twists it and says..

"Then with the next breath you say
AGS has taught the diamond cutting industry how far from the published charts they can cut."

AGS gave guidelines, PERIOD...

 

[michaelgem]

In his email Peter said he is miffed at me. Peter is the consummate gentleman and cordial at all times, so when he says he is miffed it means he is really pissed off at me.

Peter is a great guy. So I hate to have him mad at me over what seems to me to be a win-win request for AGS and those interested in a better understanding of the AGS cut grading system.

I addressed some of his concerns in a return email, but this concern of his is best addressed on PS:

“You keep saying that the charts are for cutters and consumers. The charts have never been for consumers. They are cutting guideline charts, not consumer education / grading charts. So please stop the inference.” Peter Yantzer

Let me try to answer this concern.

AGS says that these charts are for cutters. I know they have been expressly billed as cutter guideline charts a multitude of times on this forum. So they clearly are for cutters.

The problem is my saying they are for consumers. My answer is that they are all that has been made available to consumers and folks like me and others that want to understand the AGS cut grading. So if they are not for us then what is?

If AGS does not give us up to date information in some form at least as good as the charts then the old charts are all we have.

I can hear a chorus of so whats. Maybe I should mind my own business. Perhaps.

One of my interests is appraising. Appraisers have a vested interest in understanding both GIA’s and AGS’s cut grading in order to do a proper analysis, just as they need to understand the grading systems for color and clarity.

There are many others, including jewelers and savvy consumers, who have an interest in learning more about the AGS cut grading system. Few of them have the money or the time required to obtain and utilize a Sarin scanner and PGS software.

Would AGS not be better perceived and understood globally and be better served by having their grading system more correctly represented and understood?

I want to smooth things over with Peter, and I want to thank him for the following offer he has made to us. So I will stop "beating a dead horse". I know. You thought I was beating something else.

Peter writes to me:
“We’re trying to be transparent and provide you with substantive information. …. Jim thought that giving a copy to Sergey would be helpful. Work with Sergey and you guys can make and publish all the charts you want.”

Thank you, Peter.

Have a great weekend.

Michael Cowing

 

[michaelgem]

If folks can overlook the attitude they perceive in my posts, they will see that there is a lot of substance that is helpful to an understanding of diamond cut grading in general as well as that of AGS and GIA. For example, the following parametric/nonparametric discourse was not lost on Sergey and would not be lost on AGS’s mathematician, Jason Quick:

Both AGS’s and GIA’s charts are parametric representations of their grading systems. GIA’s system was developed from a statistical analysis of nonparametric data. So both AGS and GIA have nonparametric grading systems being represented by these parametric charts. The limitations on the usefulness of these charts that Strm and others point out applies equally well to the charts of both AGS and GIA.

There is no bias or agenda in this example, or in any of my attempts to answer the questioning of my reasons for wanting updated charts.

I hope some of you will reread my posts with an eye for the content, rather then the perceived attitude. A very smart friend admonished me one time by saying: “Michael, there is no room for attitude in scientific discourse.” I try to keep that in mind, but because of eagerness and impatience I often forget.

Since I am a proponent of Super Ideal cutting, I like to close with the salutation:

Ideal regards,
Michael Cowing