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

[adamasgem]

Date: 2/22/2007 11:58:40 PM
Author: strmrdr

Date: 2/22/2007 11:38:38 PM
Author: adamasgem

Just like I can provide ''masters'' for color, and can show the effects of fluorescence and lighting to my clients, those who have classic examples of cutting to illustrate the answers to questions posed by clients are free, and in fact obligated to provide that information, and let the chips fall where they may.

Big difference the color masters are not a branded stone and they are certified by an outside authority in the field.

My masters were supplied by Lazare Kaplan, and the off color masters are not necessarily cut to the same standards,

No one says that 8* is the cut master stone cept for maybe you and RockDoc and you have been paid by them at times and RockDoc has a well documented love affair with them.

I''m entitled to my opinion that they are among the top cutting, if not the best.

Neither of you is impartial when it comes to them.
Like I said if they were not identified as 8* then no issue with it.

Your comments here and in the past certainly don''t sound impartial with regard to the cutting style, let alone the brand, and there has been a concerted effort, it appears, on PS to try to destroy the image and benefits of the cutting style (whether Eightstar or New Line), and I would say that you have been among those trying to do so, for whatever reasons you have, perhaps because some of your "friends" can''t cut them.

Certainly GIA has done its best to destroy them arbitrarily because of painting, while giving EX to some of the s**t I have seen in their paridigm.


I''v know about this issue for a long time and haven''t brought it up until tonight.
See my next post.....

 

[adamasgem]

Date: 2/22/2007 10:39:13 PM
Author: strmrdr

As far as my asscher grading its simple...
Great looking symmetrical patterns in a square as possible asscher with a over 10% crown makes people who own them very happy :}
300+ and counting.

I would say that most experts consider an Asscher sytle cutting to have over a 15% crown height, and steep crown angles, ideally square. So if you are representing a 10% crown height stone as Asscher style cutting, I think that you don''t know what the hell you are doing, period.

 

[Serg]

Date: 2/22/2007 5:17:46 PM
Author: adamasgem

Date: 2/22/2007 4:17:22 PM
Author: Serg
re:SOMETIMES, because of the particular stones composite, you are going to have rather steep deduction gradients.. That's life. You see it in EVERY CUT GRADE system, including yours!!!!!!!!

Marty,

Firstly we have not cut grade. What would you then properly call the Diamond Calc performance analysis and the MSU study? I'll defer to your 'definition', if I inappropriately referred to it a 'cut grade'.

Secondly there is easy avoid such problem in Cut grade system Give the unrounded numerics, along with confidence bounds is what I suggest, and then borderline stones could be properly compared.

Is it a 0.99 or a 1.01.. rather than a 0 or 1 is what I have suggested, and the PGS software breaks it down so. Perhaps that should also be on the 'paper'. The 'high H' versus 'low G' analogy.

In third what is right AGS charts for cutters? The most conservative charts, as most have already adapted to, if they desire, I believe. The intersection of the 'best' of all grading systems is a good starting point, if the cutters are interested in that aspect. Given the seemingly overemphasis on weight retention in the vast majority of the trade because of long time arbitrary weight boundaries, this is a 'problem' not easily solved.



I know this is an 'issue' for 'planning' software and maximizing yield versus 'grade', i.e. profit, but that is a separate non linear 'optimization' decision for the cutters to make, especially if one wants to 'satisfy' or optimize both 'all' different theoretical and 'direct measurement' technologies paradigms (known or unknown).

re:The most conservative charts

Do you mean Charts with minimum number AGS0?
Please remember I showed what One type can not be conservative version other chart.

Tonight I received more candidates for AGS guideline charts. More and more interpretation coming.
for my opinion it bad situation for market and AGS. Should be official guideline from AGS with marked date.
If AGS are changing any guideline it should be clear for market.
Instead it AGS are spending efforts to nice color charts but which are not helpful for real work.

re:Give the unrounded numerics, along with confidence bounds is what I suggest, and then borderline stones could be properly compared.

+ do not DO GRADE!
DO RATING.

Forget about AGS0, forget about penalty system, forget about ideal diamond.
Give possibility improve diamond cut. For example in 2005 best diamond received RATING AGS 1367
In 2006 best diamond received RATING AGS 1520,...

conceptions of AGS0, GIA excelent are moving diamond market to deadlock. It is a cheapest tactic solution, but very bad strategically solution

re:. What would you then properly call the Diamond Calc performance analysis and the MSU study?

Cut Quality( see in page in DC):

OctoNus has not any GRADING system, OctoNus is developing RATING system with same rules for any cut diamond.
In our system cut has possibility to receive better RATING than Tolkowsky cut for example

 

[strmrdr]

Date: 2/23/2007 12:48:00 AM
Author: adamasgem

Date: 2/22/2007 10:39:13 PM
Author: strmrdr

As far as my asscher grading its simple...
Great looking symmetrical patterns in a square as possible asscher with a over 10% crown makes people who own them very happy :}
300+ and counting.

I would say that most experts consider an Asscher sytle cutting to have over a 15% crown height, and steep crown angles, ideally square. So if you are representing a 10% crown height stone as Asscher style cutting, I think that you don't know what the hell you are doing, period.

Where may I find that data?
Btw where do I find an asscher expert? arent any around here cept maybe Paul and he isnt talking about it.
Would like to chat with some :}

15% is good of course but dozens of consumers have been happy with 10%-11% a few with 9% too.
Personaly iv seen a few at 10% that rocked my world and in studying virtual stones in DC 10% will get the job done with proper angles.
Some of my favorites that Iv seen have been in the 25%+ range with tiny tables but they arent being cut anymore.

 

[Serg]

Marty,

I want clarify. We can no considered what ONE AGS CHART is more strict ( or liberal) than OTHER.
Its are quit different charts. one is much more close to GIA grading system, one is far from GIA system( I see diagonal shift between AGS charts)

 

[Serg]

Could anybody publish full ASG-PGS report for below 4 cuts( DC models) ?

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%

 

[adamasgem]

Date: 2/23/2007 1:49:45 AM
Author: strmrdr

Date: 2/23/2007 12:48:00 AM
Author: adamasgem

Date: 2/22/2007 10:39:13 PM
Author: strmrdr

As far as my asscher grading its simple...
Great looking symmetrical patterns in a square as possible asscher with a over 10% crown makes people who own them very happy :}
300+ and counting.

I would say that most experts consider an Asscher sytle cutting to have over a 15% crown height, and steep crown angles, ideally square. So if you are representing a 10% crown height stone as Asscher style cutting, I think that you don''t know what the hell you are doing, period.

Where may I find that data?
Btw where do I find an asscher expert? arent any around here cept maybe Paul and he isnt talking about it.
Would like to chat with some :}

15% is good of course but dozens of consumers have been happy with 10%-11% a few with 9% too.
Personaly iv seen a few at 10% that rocked my world and in studying virtual stones in DC 10% will get the job done with proper angles.
Some of my favorites that Iv seen have been in the 25%+ range with tiny tables but they arent being cut anymore because you only get one stone out of the rough.

To my knowledge, Asscher style cuting has been described as large cornered emerald cuts with a high crown and deep pavilion (I believe from the GIA Diamond dictionary). They tended, I believe, althogh can''t find a specific reference, to smaller tables, as you suggest, and if my memory serves me, more to the depth ratio of a 1/3 in the crown to 2/3''ds in the pavilion.

The Royal Asscher is a patented cut, necessary becuase the trade bastardized the cutting style, and the ploy that practically anything was an "Asscher cut". and I believe the Royal Asscher added pavilion steps to characterize the stone.

Your observation of "Some of my favorites that Iv seen have been in the 25%+ range with tiny tables but they arent being cut anymore because you only get one stone out of the rough." characterized the results of the cutting style giving exceptional fire for emerald cut.

Real squares seem extremely difficult to find.

Royal Asschers command a premium as they are not batardized by copycats because of patent protection.

 

[adamasgem]

Date: 2/23/2007 2:31:05 AM
Author: Serg

Could anybody publish full ASG-PGS report for below 4 cuts( DC models) ?

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%

Generate the STL fils and I''ll see about getting them run.

 

[strmrdr]

Marty re asschers: not going to do a long quote...
Yes the RA has extra pavilion steps, some badly made clones exist and an occasional good one because RA hasnt went after them.
Even RA in some recent examples have moved to smaller corners and shallower crowns but still in the high range. :{

1/3 and 2/3 would make an awesome stone but I know of no one cutting them today and a lot of the old ones were not that high.
The one original Asscher Iv seen looked close to that to my eye. 25%+ at the min.
I agree that there is a lot of crap being called an asscher these days, but there are also some awesome stones of several different styles being cut.

 

[adamasgem]

Date: 2/23/2007 1:55:30 AM
Author: Serg

Marty,

I want clarify. We can no considered what ONE AGS CHART is more strict ( or liberal) than OTHER.

Its are quit different charts. one is much more close to GIA grading system, one is far from GIA system( I see diagonal shift between AGS charts)

Sergey, as you know it is a multi dimnsional problem and small changes can effect the apparent diagonal. We don''t know where in the grade range th localized peak performance characteristics are, at last I have never seen it.

Regarding your conception of a "rating system", it makes sense, but I don''t think the "trade" is sophisticated enough to handle it, and of course the relative "rating" depends on the envirionment chosen, and until one gets (or sets) a defined envirionment, and it is accepted as a best representative to "rate" diamonds in, then we will have the disagreements. You saw this with the MSU stydy and GIA''s initial attemps at a technical solution, and they seemingly threw upp their hands, and didn''t wash them before they applied the "taste test", and you see what resulted.

The "quantitive" system you suggest vis a vie the "qualitative" systems that exist has its own pitfalls, as I have mentioned, and MIGHT be better for understanding performance factors and localized optimals for us techno geeks, but personally the trade would have a hard time with it.

I wish I had the funding and time to do some of the work I''d like to do.

Somewhere in this thread you had a link to a cut grade overlay and your reference stones. Do you present a "rating for each position such that localized optimals may be found.?

 

[Serg]

Date: 2/23/2007 2:41:22 AM
Author: adamasgem

Date: 2/23/2007 2:31:05 AM
Author: Serg

Could anybody publish full ASG-PGS report for below 4 cuts( DC models) ?

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%

Generate the STL fils and I''ll see about getting them run.

Marty, Do you have DC yet?
DC has export to binary STL( Menu\Cut\Export\binary STL)
If you have very old version, please download DC2.8.5
http://www.octonus.com/oct/download/diam_demo_down.phtml
I think DC 2.8.0 had such export too

 

[Serg]

re:Regarding your conception of a "rating system", it makes sense, but I don''t think the "trade" is sophisticated enough to handle it

It is very comfortable position for Labs, "We are doing bad service because "Trade" is not ready for good service."
What is "Trade"? Is it ONE silly person?
I sure a lot of smart, educative and active persons in "Trade"
But such service from Labs are killing best and worst parts of "Trade" in same part.
Labs are working for middle part "Trade" only. They penalty evolution.
It is reason why diamond "Trade" loses competitive activity to other Luxury "Trades

 

[diagem]

Date: 2/22/2007 9:08:58 PM
Author: Garry H (Cut Nut)
On both counts you question my competence.

I buy diamonds based on that companies grades, and have seen thousands of diamonds at their offices and bought unseen also. They even split grades G-, G G+, SI1- SI SI+. They give placement, type and black or not for clarity , and are working to give totally radical clarity info to their clients. Why would I not trust them? If other companies would do that (some do) as is the prsactice inmany other industries - then this industry would be a lot more efficient.

I am in total agreement with you on this one!!! I do it on a regular basis, and it simplifies communication between industry members..., especially when a lot of communication between industry members is via computers!!! Like I said many times before..., the biggest challenge this industry faces is getting out of its primitive business habits!!! It is happening...., but very SLOWLY!!! But I believe slow is solid way!!!

Date: 2/22/2007 8:54:10 PM
Author: strmrdr

Date: 2/22/2007 8:30:26 PM
Author: Garry H (Cut Nut)

Date: 2/22/2007 8:27:47 PM
Author: Garry H (Cut Nut)

Storm Roc is correct - it is nice to be able to simplify things, and the AGS ASET charts do that - but they are purely face up. Which is why I direct people to look at fancies thru an A
SET while rocking the stone.

I saw this stone yeasterday - It is amazingly stunning in person (with 2 eyes) yet you would have trashed it I am sure based on its ASET view, and AGS would probably never have looked at these proportion sets for their system.

oops

depends on how far away one was viewing it and what lighting.
Bet I could find a common viewing postion it sucked in where one with a better ASET image would rock.

Again you question my competence. I look at diamonds, and their ASET images Storm. Lots of diamonds. I looked at this near the window, under office lighting, under the desk, in the hall with halogens. You would say Do not buy it, and you would do a shopper a gross disservice. Agreed big time again..., Every Diamond that I purchase will go through my personal way of testing it for beauty!!! I will play with the Diamonds in many lighting options..., from pure direct midday sunlight to almost complete dark-rooms. I find myself many times carrying a Diamond on me for the purpose studying its beauty behavior in different lighting...., (''different'' I mean light that is common to people not in the industry...)
And believe me..., you learn a lot!!!! Much more than just office light environments (like I would imagine the majority of Diamonds get tested!!!)

So stop bighting Roc''s head off and listen and learn. Debate by all means. But play the topic and not the man. I say that here because I know this is a consumer totally free thread.

 

[adamasgem]

Date: 2/23/2007 5:42:04 AM
Author: Serg

Marty, Do you have DC yet?
DC has export to binary STL( MenuCutExportinary STL)
If you have very old version, please download DC2.8.5
http://www.octonus.com/oct/download/diam_demo_down.phtml
I think DC 2.8.0 had such export too

Sergey
1) FYI The digital signature on the exe from the link identifies the non hasp version as build 375 and not 379 like the page says, which is what I already have.

Can you send me asc files and I''ll convert to stls.

 

[Serg]

Date: 2/23/2007 8:53:45 AM
Author: adamasgem

Date: 2/23/2007 5:42:04 AM
Author: Serg

Marty, Do you have DC yet?
DC has export to binary STL( MenuCutExportinary STL)
If you have very old version, please download DC2.8.5
http://www.octonus.com/oct/download/diam_demo_down.phtml
I think DC 2.8.0 had such export too

Sergey
1) FYI The digital signature on the exe from the link identifies the non hasp version as build 375 and not 379 like the page says, which is what I already have.

Can you send me asc files and I''ll convert to stls.

Marty, Please check email

 

[diagem]

Date: 2/22/2007 8:36:49 PM
Author: Garry H (Cut Nut)

Date: 2/22/2007 11:33:40 AM
Author: RockDoc
I just don''t see how charts can be used for grading. I think it is irresponsible to issue a grade just based on the numbers. There are far too many other factors that can affect light performance in a stone.

How the crystal was oriented when being cut, I believe can have a significant affect on the resultant light performance when turned to save weight.

I have also observed light performance differences relevant to TRANSPARENCY of the stone. I am surprised that this is almost never mentioned in the grading of light performance/cut grading. This is a characteristic that charts or scans can''t discern. It can only be observed and ''rated'' with highly experienced and trained human eyes. Currently there is no standard of transparency that the gemological community can rely on by using master stone examples. It''s just a judgment call made by those who take this into consideration when visually examining the stone. One also needs to question as what is acceptable and what isn''t.

I''m not even sure if cutters can ''control'' the affect. But I have certainly seen a difference in various diamonds, where some have incredibly clear transparency and other don''t quite display this. Unfortunately, no chart, set of proportions, or ray tracing can analyze this characteristic. I think that whatever happens, happens and no one really knows the extent of the affect, until the facteting and polishing is completed. I do suspect, it is not taken into consideration, by the majority of graders, cutters and labs.

We''d all like to have a simplistic way to get to the ''edge'' of what constitutes the best or the next best grading for cut, but using just a chart to determine this, is a bit lacking in its scope of accuracy.

Rockdoc

I agree and disagree Roc

Firstly a stone must have graining or clouds to have a drop in transperancy, and we can usually pick this up just with a loupe - but it is not an issue as to the orientation of the (cubic) crystal if the stone does not have these problems.

I have agreed with you before however that there are indeed many stones (maybe 5%) with some degree of transperancy issue. Garry, may I ask how you got to Approx. 5%? And from what type of Diamonds? low-mid-high range? Colorless or fancy colors?

And no one seems to address it in terms of a grading system (other than 1 Indian firm who operate the best grading lab I have ever come across for the sale of their own goods - but hey Storm, you could never trust a vendor could you?). They list luster on a scale of Ex >>>>, and they only ever give VG as their top grade (maybe it is like ABC color?

). You just said "Firstly a stone must have graining or clouds to have a drop in transparency".
I believe most professional Labs. do address issues as clouds and internal graining and describe them on their reports... (I know that at least the GIA does...). I would think any excess of internal inclusions would have affect the transparency of a Diamond.
Another interesting subject you just mentioned is "luster" how do the Indian firm define luster of Diamonds?

So if anyone want to develop their own transperency grading methodology they would be doing us all a great favor.

 

[adamasgem]

Date: 2/23/2007 5:42:04 AM
Author: Serg

Date: 2/23/2007 2:41:22 AM
Author: adamasgem

Date: 2/23/2007 2:31:05 AM
Author: Serg

Could anybody publish full ASG-PGS report for below 4 cuts( DC models) ?

6 mm 80 LG P41 Cr35 T57
1) Girdle( In bezel) 3% Star 50% DC/LRM 0.98/LRS 0.97/DZM 0.96/FE 1.0
2) Girdle( In bezel) 3.5% Star 50% DC/LRM 0.98/LRS 0.97/DZM 0.96/FE 1.0
3) Girdle( In bezel) 3% Star 55% DC /LRM 0.99/LRS 0.97/DZM 0.97/FE 1.0
4) Girdle( In bezel) 3.5% Star 55% DC /LRM 0.99/LRS 0.97/DZM 0.96 /FE 1.0

Generate the STL fils and I''ll see about getting them run.

STLS generated, I''ll try to get the PGS run..
Note the slight differences in the DC metrics
Also note that the DC metric DOES NOT indicate that it rates FIRE, which AGS PGS does..

Sergey.. when I locked the table, ca, pa,star and entered the LGF, and then tried to increment or type in the girdle, it kept changing what I typed in, the depth was floating. After 3 or 4 tries it finally took. ??????

 

[adamasgem]

Date: 2/23/2007 10:11:13 AM
Author: DiaGem

Date: 2/22/2007 8:36:49 PM
Author: Garry H (Cut Nut)


I agree and disagree Roc

Firstly a stone must have graining or clouds to have a drop in transperancy, and we can usually pick this up just with a loupe - but it is not an issue as to the orientation of the (cubic) crystal if the stone does not have these problems.

I have agreed with you before however that there are indeed many stones (maybe 5%) with some degree of transperancy issue. Garry, may I ask how you got to Approx. 5%? And from what type of Diamonds? low-mid-high range? Colorless or fancy colors?

And no one seems to address it in terms of a grading system (other than 1 Indian firm who operate the best grading lab I have ever come across for the sale of their own goods - but hey Storm, you could never trust a vendor could you?). They list luster on a scale of Ex >>>>, and they only ever give VG as their top grade (maybe it is like ABC color?

). You just said ''Firstly a stone must have graining or clouds to have a drop in transparency''.
I believe most professional Labs. do address issues as clouds and internal graining and describe them on their reports... (I know that at least the GIA does...). I would think any excess of internal inclusions would have affect the transparency of a Diamond.
Another interesting subject you just mentioned is ''luster'' how do the Indian firm define luster of Diamonds?

So if anyone want to develop their own transperency grading methodology they would be doing us all a great favor.

I can''t keep track of who asked for a transparancy grading system, but it (transparancy) inherently effects color grading.. and it is mentioned as a part of clarity grading, so there might be a lot of double pork chopping going on.

In the same manner, color grade (internal absorption) effects light performance factors such as brilliance (light return) and fire..

 

[diagem]

Date: 2/23/2007 10:59:51 AM
Author: adamasgem

Date: 2/23/2007 10:11:13 AM
Author: DiaGem

Date: 2/22/2007 8:36:49 PM
Author: Garry H (Cut Nut)


I agree and disagree Roc

Firstly a stone must have graining or clouds to have a drop in transperancy, and we can usually pick this up just with a loupe - but it is not an issue as to the orientation of the (cubic) crystal if the stone does not have these problems.

I have agreed with you before however that there are indeed many stones (maybe 5%) with some degree of transperancy issue. Garry, may I ask how you got to Approx. 5%? And from what type of Diamonds? low-mid-high range? Colorless or fancy colors?

And no one seems to address it in terms of a grading system (other than 1 Indian firm who operate the best grading lab I have ever come across for the sale of their own goods - but hey Storm, you could never trust a vendor could you?). They list luster on a scale of Ex >>>>, and they only ever give VG as their top grade (maybe it is like ABC color?

). You just said 'Firstly a stone must have graining or clouds to have a drop in transparency'.
I believe most professional Labs. do address issues as clouds and internal graining and describe them on their reports... (I know that at least the GIA does...). I would think any excess of internal inclusions would have affect the transparency of a Diamond.
Another interesting subject you just mentioned is 'luster' how do the Indian firm define luster of Diamonds?

So if anyone want to develop their own transperency grading methodology they would be doing us all a great favor.

I can't keep track of who asked for a transparancy grading system, but it (transparancy) inherently effects color grading.. and it is mentioned as a part of clarity grading, so there might be a lot of double pork chopping going on. Right, so body-Color in a Diamond should effect transparency, am i right?

In the same manner, color grade (internal absorption) effects light performance factors such as brilliance (light return) and fire..

 

[adamasgem]

Date: 2/23/2007 11:10:53 AM
Author: DiaGem

Date: 2/23/2007 10:59:51 AM
Author: adamasgem

Date: 2/23/2007 10:11:13 AM
Author: DiaGem

I can''t keep track of who asked for a transparancy grading system, but it (transparancy) inherently effects color grading.. and it is mentioned as a part of clarity grading, so there might be a lot of double pork chopping going on. Right, so body-Color in a Diamond should effect transparency, am i right? By definition it does

 

[diagem]

Date: 2/23/2007 11:15:36 AM
Author: adamasgem

Date: 2/23/2007 11:10:53 AM
Author: DiaGem

Date: 2/23/2007 10:59:51 AM
Author: adamasgem

Date: 2/23/2007 10:11:13 AM
Author: DiaGem

I can''t keep track of who asked for a transparancy grading system, but it (transparancy) inherently effects color grading.. and it is mentioned as a part of clarity grading, so there might be a lot of double pork chopping going on. Right, so body-Color in a Diamond should effect transparency, am i right? By definition it does

So when GIA (for example)grades "Fancy "DEEP''" on colored Diamonds..., some cases will be Diamonds that their body-color effect their transparency...
Am i ok so-far?

 

[Garry H (Cut Nut)]

A lot of threads running at once.

1. Michael, learn how to use the quote button. Call someone if you need to.

2. I instigated a grading system called HCA. I now refer to it as a system to restrict online searches to those that are more likely to be good. Sergey also has tools that rate diamonds. These are not grading systems.

3. Diagem - the Indians use ''Luster'' to unambiguosly describe diamonds that have less transperancy and brightness / fire. GIA and others use trade jargon terms to describe the same results to trick consumers.

We have a very sick industry that is badly served by our authorities.

It is time for a change. Many of you reading this (lurkers) agree, and others who feel afronted do too. Those participating feel the pressure of the wave.

 

[diagem]

Date: 2/23/2007 11:59:05 AM
Author: Garry H (Cut Nut)
A lot of threads running at once.

1. Michael, learn how to use the quote button. Call someone if you need to.

2. I instigated a grading system called HCA. I now refer to it as a system to restrict online searches to those that are more likely to be good. Sergey also has tools that rate diamonds. These are not grading systems.

3. Diagem - the Indians use ''Luster'' to unambiguosly describe diamonds that have less transperancy and brightness / fire. GIA and others use trade jargon terms to describe the same results to trick consumers.

We have a very sick industry that is badly served by our authorities.

It is time for a change. Many of you reading this (lurkers) agree, and others who feel afronted do too. Those participating feel the pressure of the wave.

What Indians used as the term "first water" back in the old days evaluate rough or semi-cut/polished diamonds, do you translate that term to some sorth of "luster"?
What jargon do they use to trick consumers?

 

[Garry H (Cut Nut)]

DiaGem You asked how do labs trick consumers (and many retailers)?

I have enlarged your comment to make an answer:-

Date: 2/23/2007 11:10:53 AM
Author: DiaGem

Date: 2/23/2007 10:59:51 AM
Author: adamasgem

Date: 2/23/2007 10:11:13 AM
Author: DiaGem

Date: 2/22/2007 8:36:49 PM
Author: Garry H (Cut Nut)


I agree and disagree Roc

Firstly a stone must have graining or clouds to have a drop in transperancy, and we can usually pick this up just with a loupe - but it is not an issue as to the orientation of the (cubic) crystal if the stone does not have these problems.

I have agreed with you before however that there are indeed many stones (maybe 5%) with some degree of transperancy issue. Garry, may I ask how you got to Approx. 5%? And from what type of Diamonds? low-mid-high range? Colorless or fancy colors?

And no one seems to address it in terms of a grading system (other than 1 Indian firm who operate the best grading lab I have ever come across for the sale of their own goods - but hey Storm, you could never trust a vendor could you?). They list luster on a scale of Ex >>>>, and they only ever give VG as their top grade (maybe it is like ABC color?

). You just said ''Firstly a stone must have graining or clouds to have a drop in transparency''.
I believe most professional Labs. do address issues as clouds and internal graining and describe them on their reports... (I know that at least the GIA does...). I would think any excess of internal inclusions would have affect the transparency of a Diamond.
Another interesting subject you just mentioned is ''luster'' how do the Indian firm define luster of Diamonds?

So if anyone want to develop their own transperency grading methodology they would be doing us all a great favor.

I can''t keep track of who asked for a transparancy grading system, but it (transparancy) inherently effects color grading.. and it is mentioned as a part of clarity grading, so there might be a lot of double pork chopping going on. Right, so body-Color in a Diamond should effect transparency, am i right?

In the same manner, color grade (internal absorption) effects light performance factors such as brilliance (light return) and fire..

An honest comment on a lab report might be somethiong like:

This diamond does not sparkle much

 

[diagem]

Date: 2/23/2007 12:30:52 PM
Author: Garry H (Cut Nut)
DiaGem You asked how do labs trick consumers (and many retailers)?

I


An honest comment on a lab report might be somethiong like:

This diamond does not sparkle much

I am assuming you say that for the consumers sake...
Most people identify sparkle..., maybe they have no experience with different level of sparkle that we see and identify everyday in quantities!!! So you might have a point..., but only partially..., I think sparkle is judged on individualism... everybody likes his/her own sparkle!!!!

Now, I personaly love Diamonds that have limited sparkle..., thats why I think it is judged on a stone by stone basis...

 

[michaelgem]

Date: 2/23/2007 1:55:30 AM
Author: Serg

I want clarify. We can no considered what ONE AGS CHART is more strict ( or liberal) than OTHER.

Its are quit different charts. one is much more close to GIA grading system, one is far from GIA system( I see diagonal shift between AGS charts)

Sergey

In order to second Sergey''s points and insure their consideration, I''ll rephrase them the way I would say it. He is observing and has documented for us several contradictions among AGS''s published grading charts and data.

It is clear that Sergey, with his credibility as an accomplished Russian reasearch scientist cotributing to knowledge in this field, has the same belief that AGS would be doing themselves and us a favor by clarifying their updated range of Ideal 0.

To clarify. We do not consider one AGS Chart as more strict (or liberal) than another.

There are quite different charts released by AGS. One is closer to the GIA grading system and one is far from the GIA system. I see a diagonal shift between the AGS charts.

 

[diagem]

Date: 2/22/2007 8:27:47 PM
Author: Garry H (Cut Nut)

Date: 2/22/2007 6:34:56 PM
Author: strmrdr
Personally I think a new chart wouldn''t help, someone could still take the ASET/Dispersion maps cut a combo that does well on all 3 and get a 0 for stone not on the charts and start this conversation all over again.

Storm Roc is correct - it is nice to be able to simplify things, and the AGS ASET charts do that - but they are purely face up. Which is why I direct people to look at fancies thru an A
SET while rocking the stone.

I saw this stone yeasterday - It is amazingly stunning in person (with 2 eyes) yet you would have trashed it I am sure based on its ASET view, and AGS would probably never have looked at these proportion sets for their system.

Garry, sorry to reverse but why only Fancies?

 

[Serg]

re:6 mm 80 LG P41 Cr35 T57
1) Girdle( In bezel) 3% Star 50% DC/LRM 0.98/LRS 0.97/DZM 0.96/FE 1.0
2) Girdle( In bezel) 3.5% Star 50% DC/LRM 0.98/LRS 0.97/DZM 0.96/FE 1.0
3) Girdle( In bezel) 3% Star 55% DC /LRM 0.99/LRS 0.97/DZM 0.97/FE 1.0
4) Girdle( In bezel) 3.5% Star 55% DC /LRM 0.99/LRS 0.97/DZM 0.96 /FE 1.0
Marty: Generate the STL fils and I''ll see about getting them run.STLS generated, I''ll try to get the PGS run..
Note the slight differences in the DC metrics
Also note that the DC metric DOES NOT indicate that it rates FIRE, which AGS PGS does..


Marty,
I do not need any software for statement what such similar diamonds should receive same rating, grade.../ Difference 1% in rating is quit normal, but difference in 3 grades for 10 steps grade system is quit abnormal.
I do not know about reason this mistake in AGS grade( two possibility: Or AGS change grade system ( and these grades from different software) or AGS-PGS has big problems with continuity in point)

 

[Serg]

re:Also note that the DC metric DOES NOT indicate that it rates FIRE, which AGS PGS does..

Marty,

For me very strange hear it from you. It is simple AGS advertising for consumers and "Trade"

Do you know AGS Fire metric? Do you know verifications tests for AGS fire metric?

A lot of people can calculate dispersion angle, weight it by intensity and area and say: we have Fire metric.
And will you believe such Fire metric.
when Fire is bigger:
1) for One big color flash or for two color flashes with half area( or diameter) from big flash
2) For one bright flash or for several dim flashes

and other a lot of simple questions/ Do you know AGS answers? if not what does AGS PGS? ( something but why grade fire)

 

[adamasgem]

Date: 2/23/2007 3:34:56 PM
Author: Serg

re:6 mm 80 LG P41 Cr35 T57
1) Girdle( In bezel) 3% Star 50% DC/LRM 0.98/LRS 0.97/DZM 0.96/FE 1.0
2) Girdle( In bezel) 3.5% Star 50% DC/LRM 0.98/LRS 0.97/DZM 0.96/FE 1.0
3) Girdle( In bezel) 3% Star 55% DC /LRM 0.99/LRS 0.97/DZM 0.97/FE 1.0
4) Girdle( In bezel) 3.5% Star 55% DC /LRM 0.99/LRS 0.97/DZM 0.96 /FE 1.0

Marty: Generate the STL fils and I''ll see about getting them run.STLS generated, I''ll try to get the PGS run..
Note the slight differences in the DC metrics
Also note that the DC metric DOES NOT indicate that it rates FIRE, which AGS PGS does..


Marty,
I do not need any software for statement what such similar diamonds should receive same rating, grade.../ Difference 1% in rating is quit normal, but difference in 3 grades for 10 steps grade system is quit abnormal.
I do not know about reason this mistake in AGS grade( two possibility: Or AGS change grade system ( and these grades from different software) or AGS-PGS has big problems with continuity in point)

SERGEY.. DON''T GO OFF HALF COCKED. LOOK AT WHAT I SENT YOU. AS I SAID PRIVATELY TO YOU, the problem you choose to address publically arises because DIAMONDCALC can, and did, generates STLS that are BOGUS, just as Sarin had problems with, and were readily apparent in OGI STL previously in another thread.

I SENT YOU DIAMONDCALC generated binary STLS, that had some MINOR issues, like three colinear (or coincident) points, and GARBAGE IN, GARBAGE OUT. It is impossible for ANY software to trap all the potential CRAP that it is given for input, and you are NOT WITHOUT BLAME HERE. You chose NOT TO LOOK AT THEM Before trying to create a PUBLIC FLAP.

In the files you just sent me, one of the files had crown facet STL''s which were not identical, and one would expect all points on a virtual facet to lie on the same plane.