GIA Diamond Cut Grading: Problems with Diamond Dock

[WinkHPD]

Date: 3/19/2006 2:44:55 PM
Author: JohnQuixote

All you rugged, smart looking guys are enough to make me want to go work out and read a book.

LOL! Bring it to Vegas, we can read it together when the discussion gets too heavy between the genius''s. Better yet, get a picture of you with one of your bands.

Wink

 

[adamasgem]

Date: 3/19/2006 12:31:48 PM
Author: Rhino

Date: 3/18/2006 12:08:28 AM
Author: michaelgem

The point was made to me that the top grade in a 5-grade system such as GIA’s would better be compared to the top two grades in a 10-grade system, such as AGS’s. The agreement between them is even better on that basis.

This is a good point Mike. I would make one correction though. AGS is actually an 11 grade system instead of a 10.

Peace,

Rhino..

The point of Michael''s IS NOT A GOOD ANALOGY, in my opinion, as the example posted in this thread of a theoretical purely symmetric GIA EX that would get an AGS 4 clearly illustrates. There will be AGS 0''s, 1''s, 2''s, 3''s 4''s, and maybe worse within the GIA EX range. And GIA might give an AGS 0 a grade of VG or G (especially in the case of painted girdles, where it appears GIA completely and arbitrarily discounts them).

On the opposite side, I AGREE WITH GIA, for what it is worth, that VG and EX polish should not exclude a stone from a an AGS 0 overall cut grade, as is AGS''s current practice, I believe.

There is NOT a linear uniform distribution of grades in EITHER SYSTEM, given the table/crown/grdle/pavilion ( n space) parameter set (all other factors [stars, culet, lower girdles] being equal). And it also might be impossible to figure out given the constantly changing definitions and/or different of some words like "thin to slightly thick".

And the case of AGS basing grades on "actual scans" and GIA on averaged, rounded values further complicates differences.

At best we can look at what GIA and AGS would each give a theoretically symmetric stone set for the published parameter sets, like the "illegal" (from GIA''s perspective) comparisons I had posted (where someone else did the "illegal work" and I did the posting and color coding, as I disclosed) on an earlier thread.

John Quiote then did a volumetric count of these data on the FAQ, showing a 5 to 1 volumetric comparison between an AGS 0 and GIA EX. A much smaller 10 ring, with a small fraction of AGS''s 10 ring falling outside GIA''s EX ring.

Maybe "acceptable" for the masses, but subject to vast differences in prices/discounts in the trade, most (if any) of which will not be passed to the consumer. It it my fear, based on almost 100% certainty, that GIA EX''s will be passed off as equivilant in cutting standards as AGS 0''s or even 1''s.

 

[tarssarb]

Date: 3/18/2006 11:30:39 PM
Author: michaelgem

I want to add further clarification as regards the “major” painting done to obtain the performance characteristics of the painted diamonds with which we are all familiar.

I noted that this amount of painting is major enough to drop these diamonds from the top grades in both GIA’s and AGS’s grading systems. This is a fact obtained from and recently told to me by both organizations.

That is one of the commonalities between AGS and GIA that I am pointing out.

In discussion with AGSL I was told cutters should restrict their painting within 4° for an AGS0. Supporting this statement was a list sent me of 1500 proportion sets, having various degrees of painting and digging, which has been available to cutters wishing to obtain AGS 0 cut grades. The greatest amount of painting on this list was 3.75°

You cannot obtain the optical properties that are the hallmark of these particular diamonds with a four degree or less painting. Typically, seven or more degrees of painting is needed.

Due to all the uproar these statements occasioned, I called AGSL again to make doubly sure of my facts.

I learned this afternoon that there are no hard and fast, published boundaries to painting that preclude a diamond from getting an AGS 0. On a case by case basis, the proportion set would have to be analyzed for brightness, contrast, and dispersion to see if a given instance of painting makes AGS 0 or not. The four degrees mentioned is a recommendation.

Anyone is invited to submit data files to see if the degree of painting they are doing makes AGS0 or not.

Michael Cowing

www.acagemlab.com

So if you have a ags000 from mid feb 2006 ad it exhibits painting (girdle ~1-4%) and matching lightscope, does that mean it is to a degree that the performance isn''t significantly different from a standard girdle ags000 from mid feb 2006? What a bummer this thread just came out!

Can someone summarize in a bullet point effect what the negative of such painitng can be: less contrast, less light return, less dispersion from the software simulations?

Does this issue become more important for stones in a bezel mount? Is this really something to watch for particularly when the size is by the critical carat weights (1.0xx)?

 

[adamasgem]

Date: 3/19/2006 3:44:42 PM
Author: tarssarb

So if you have a ags000 from mid feb 2006 ad it exhibits painting (girdle ~1-4%) and matching lightscope, does that mean it is to a degree that the performance isn''t significantly different from a standard girdle ags000 from mid feb 2006? What a bummer this thread just came out!

Don''t misread or misinterpret the comments presented regarding painted versus non painted cutting styles.
In General one can say
1) Painting gives more edge to edge brilliance, but might slightly reduce contrast as the available light is distributed differently in the stone
2) Painting gives a differnet "look" to the diamond
3) Painting may or may not change a "metric" for brightness/brilliance, because "metrics" are based on fixed lighting environments.

There are trade offs with painting, just as there are tradeoffs with crown/pavilion angle combinations, especially in the "fire" they produce

Can someone summarize in a bullet point effect what the negative of such painitng can be: less contrast, less light return, less dispersion from the software simulations?
Very hard to "summarize", other than painting, combined with super optical symmetry, and the correct "angles", helps produce striking broadflash fire. Non symmetric stones might have more "scintilation" but that may get lost depending on the viewing distance..

Does this issue become more important for stones in a bezel mount? Is this really something to watch for particularly when the size is by the critical carat weights (1.0xx)?

ll one can say is that the appearance in a bezel closed back mounting is not "helped" (or confused or hindered), so to speak, by light entereing from the pavilion.
There are so many non bezel set types of settings (including gallary finishing), skin color, lighting environments, viewing angles, etc that it is hard to make a difinative statement. Garrys pictures on this thread of lighting environments sort of bear this out.

One can note that both GIA and AGS published analyses are all based on closed back (bezel set) diamonds.

 

[michaelgem]

Repetition with clarification helps get ideas across that tend to get lost in all the NOISE.

Regarding the “major” painting done to obtain the performance characteristics of the painted diamonds that a lot of us know and love:

This amount of painting is major enough to drop these diamonds from the top grades in both GIA’s and AGS’s grading systems. This is a fact obtained from and recently told to me by both organizations.

That is one of the commonalities between AGS and GIA. They have both expressed to me their stated belief that painting to the degree we are discussing has negative optical consequences for beauty when compared to the same diamond with normally indexed top halves.

You cannot obtain the optical properties that are the hallmark of these particular diamonds without a large degree of painting, which both organizations say has negative optical consequences for aspects of diamond beauty.

They have multiple reasons, not all in common, for their belief that painting is less desirable than regular indexing.

Before anyone gets their "knickers in a twist" all over again, let me go on record as saying this has me wondering:

Have not major players in the diamond industry, at GIA, and at AGSL lauded these diamonds on several occasions as premier examples of the best diamond cutting has to offer?
Evidently, GIA''s paired comparison tests and AGSL''s Aset and other analysis have caused their respective organizations to rethink and change their positions on these diamonds with major painting.

Michael Cowing

www.acagemlab.com

 

[JohnQuixote]

AGS has an 11 level system. GIA has 5 levels.

Using EX/Ideal comparison charts from this thread (disclaimers noted there) I pulled some graphics for the top grades only. Across the 10 charts are a total of 544 proportions combinations allowed in EX and/or Ideal. Combos span CA 31.5-37 in .5 increments / PA 40.2-41.8 in .2 increments / T 52-62 in 1% increments.

Of the 544 combinations:

GIA EX only = 435
In Common = 80
AGS Ideal only = 29
(Pie Chart)

GIA EX total: only+common = 515
AGS Ideal total: only+common = 109
(Bar Graph)

 

[oldminer]

Years ago, 1986-88, when I made up the initial AGA Cut Class grades the 1A was narrow and after a long time I conceded it was too narrow to be commercially viable. It was strict to Tolkowsky and stones in that narrow range are truly great stones. I know now that 1A didn''t cover all the possibly fine stones, but I had an unrealsitstic view of the market and the way the trade views presentation of the facts. I never made it more broad, but stuck to the basic truth that it revealed about where the best were known to be.

Now, maybe AGS has taken the high road and will find out what I learned quite a few years back. Too narrow a definition of "the best" won''t win you any friends in the marketing plans of major sellers. On the other hand, the GIA looks as if it decided to finally give the much requested cut information, but make the top grade broad enough to cover way more diamonds than what ought to be accepted as "the best". The ones AGS has chosen and the ones GIA and AGS hold in common might make an excellent compromise if they are in a continuous set of parameters. Leaving off the rest of the GIA stones might allow all the world to proceed to create some sort of agreed "standard" for the time being.

It seems so unproductive to criticize without searching for the common ground solution that could help us all carry on. In time, we''ll do better still.

 

[Rhino]

Date: 3/19/2006 12:44:20 AM
Author: Garry H (Cut Nut)

The stone I studied in the journal article is not the most extreme example - it is more extreme than Rhino''s though. It has a slightly thickish girdle - a stone can have steeper deeper proportions and a thin girdle and scrape in to gIA''s grades with much lower AGS grades.

And then there is the stone that gets AGS 1 light performance and GIA Poor.

Again I would like someone to find a GIA Excellent stone we can scan and send to AGS that is near the GIA steep deep boundary. (Wink / Peter''s example has not been graded by gIA - it is a virtual stone - for that reason Wink, it could outperform a real stone with even the tinyest sym variations - so that could explain a differnece between DiamCalc / chart predictions and AGS actual ASSET data).

I''m in the process of hunting down such a stone Garry. At this point not an easy find from my regular supplliers. I would think however that if a stone was located with the identical optical signature of those same stones the tests would be as valid.

One point I would like to make however regardless of the system a person uses or what report they consult. When a stone falls on the fringes or outskirts of a cut grade, aren''t we all going to encourage they look at the diamond anyhow? Ya know ... even if we take the cream of the crop stones that fall within both systems top grades, you have a number of varying appearances that qualify as ideal. Think about it ... you have lower halves ranging from 70% and up to 85% that qualify as ideal in both systems. Put one of these alongside the other and with ideal slope angles you have 2 very different looking diamonds eh?

Peace,

 

[Rhino]

Date: 3/19/2006 5:55:21 AM
Author: Garry H (Cut Nut)
The photo''s in the journal article http://journal.pricescope.com/Articles/37/10/GIA-Excellent-Cut-Grade-Case-Study.aspx of the CZ''s werre taken rather hurriedly.
(and it is not easy with my little hand held camera)

So I took a few more - this lot are taken during the day in offices and my store. Some of the office ones have light filtered through a window as well as overhead fluoro.

Good stones on the left.
The GIA diamond dock photo of the same stones are on the gray tray.

Hey mate,

I have some commetary and questions to offer regarding your article which I found very interesting. Instead of a barrage of questions/comments let me begin by asking ...

The cubic zirconia you are using to make this comparison, the stone on the left in your pictures ...

1. What are the measurements (dmc file preferred)?
2. Is the girdle painted?

Peace,

PS: I wasn''t aware we could post .dmc files here!!! How excellent!

 

[Rhino]

Date: 3/19/2006 4:06:32 AM
Author: Garry H (Cut Nut)

Labs should work on grading diamonds or 3D models - they should never be grading based on proportions.

Actually, when you think about it Garry ... when the grader has gained the proportions, a visual analysis follows and if the degree of painting or digging impacts appearance only then is it graded lower. I''ve recently been scanning in some old stock stones and checking their grades via the GIA FacetWare on our Sarin. One stone comes to mind ... the stone got a VG cut grade according to the proportions however digging was done to the extent where the stone would be degraded to the next grade down according to other stones I have examined in that grade.

I think it all boils down to a matter of understanding how they arrived at the conclusions they have. It has taken me some time to study and investigate but once you get a handle on it, its really not the difficult.


I''ll share something else interesting with ya. Observing diamonds in this sort of consistent viewing environment has given me a greater appreciation for shallow/shallow combos and the HCA mate.

It is also given me a better appreciation of your personal preference for these types of stones, while at the same time understanding why they take the hits they do in both AGS and GIA systems.


Here is a shot of a shallow/shallow next to an OEC steep/deep under the diamonddock.

 

[Rhino]

Date: 3/19/2006 2:15:42 PM
Author: michaelgem

Hi Bill,

Re: Something I am curious about, and don''t think it is expressed as an attack, but gotta ask you why is the avatar you selected an avatar with a wizard using a crystal ball? Rockdoc

Your question prompted me to replace the arbitrarily selected wizard avatar with this new one.

Hope it is not too disturbing. I am not good looking like Garry and Jonathan, nor can I strike an athletic pose like Wink.

Michael

LOL... I was going to say ... nice mugshot Mike.

 

[Rhino]

Date: 3/19/2006 2:25:43 PM
Author: adamasgem

Date: 3/19/2006 12:31:48 PM
Author: Rhino
Catching up here as time allows.

Firstly ... Garry, thank you for pointing out the truth of my statement.

Hi Marty,

In regards to this comment ...

Date: 3/18/2006 3:18:06 AM
Author: adamasgem

If I were you, I would watch myself relying on your ''source''. If you had taken the trouble to check, you would find that the gem file that Johnathon posted as being from the steep/deep with a supposedly 35.08/41.15 crown/pavilion, really has crown angles, according to the export of the asc file, ranging from approx 34.2 to 34.35 and pavilion angles 40.72 to 40.86, unless I completely misread the ascii text file created from the gem file. Convenient misleading mistake?
(Or was some version of GIA rounding used?

)

As stated in that thread, Sergey had asked me for the Gem file comparisons of the 2 H&A diamonds, one painted one without. NOT the original comparison I posted. Per Sergey''s request I gave him precisely what he asked for.

The original comparison was indeed of a 35.1/41.2. I had posted the proportion data of the original comparisons as the very first graphics in that thread.


I, and others, had previously requested that you post the gem or dmc files of the stones you used in your ''study'', which was what the thread was about, steep/deep versus painted, so if I made a mistake in assuming that that was the post(s) you were referring to, I sincerely APPOLOGISE, if I made the wrong assumption. Again, would you please post the appropriate files requested. I becomes a problem to go back and reread an entire thread if things are not made clear.

Not a problem Marty. Garry has suggested .gem files. What is your preference?

 

[Rhino]

Date: 3/19/2006 1:00:09 PM
Author: Serg


I do not like lost time in empty discussion more. We need more hard facts.

I am ready invest 5.000-10.000$ to small MSS

Part 1 GIA Excellent
1) Crown is fix
2) Pavilion step 0.2 degree. 40.6, 41, 41.2, 41.4, 41.6



Part 2
click Painted crown. Same crown Pav 40.6, Pav 40.4( I will try receive just Good here)




Part 3



Some GIA very good ( 3-4 diamonds)
40.4 , 40.8 + some other diamonds




All ideal symmetry. Clarity an color are good for sells. Diameter 5-6 mm

I will send all diamonds to GIA and AGS.

This MSS will available for different appraisers and consumer research at least 3 months.

Welcome to invest Money, Time, Ideas, service. Hope Garry will help.

Our study will open during all steps.

Sergey,

I too am interested in garnering results for this as well. I think I know some manufacturers (MSS?) who are up for the task. Matter of fact, Paul Slegers, if we give him a model can basically duplicate it. I recently had a feww new stones cut by him for experimentation and research on a new line we are considering to stock and he did a rather remarkable job of duplicating the DiamCalc model I forwarded to him. If you''d like to compare his results with the model I sent I''ll show you the comparisons in email. I would be willing to put up some cash as well for this and will help sell the test stones once all the testing is complete by whomever you have participate.

Peace,

 

[Rhino]

Date: 3/19/2006 2:44:55 PM
Author: JohnQuixote

Date: 3/19/2006 2:15:42 PM
Author: michaelgem


Hi Bill,

Re: Something I am curious about, and don''t think it is expressed as an attack, but gotta ask you why is the avatar you selected an avatar with a wizard using a crystal ball? Rockdoc

Your question prompted me to replace the arbitrarily selected wizard avatar with this new one.

Hope it is not too disturbing. I am not good looking like Garry and Jonathan, nor can I strike an athletic pose like Wink.

Michael

All you rugged, smart looking guys are enough to make me want to go work out and read a book.

LOL

 

[adamasgem]

Date: 3/19/2006 7:03:24 PM
Author: Rhino

Date: 3/19/2006 2:25:43 PM
Author: adamasgem

Not a problem Marty. Garry has suggested .gem files. What is your preference?

Thanks RRhino,
I guess gem files will have to do, as regular dms files may be too large for posting on PS with the 100K limit. DMC''s would be better, as it seems that the angles are not readily available when you use DiamondCalc and import gem files.

I tried using gem files with GemAdviser but it expired so I have to download a new version. I don''t know whetehr it wil give the min maxes,ect I was lokkking for, like the full blown dmc helium files..

 

[Rhino]

Date: 3/19/2006 3:36:35 PM
Author: adamasgem

Date: 3/19/2006 12:31:48 PM
Author: Rhino

Date: 3/18/2006 12:08:28 AM
Author: michaelgem

The point was made to me that the top grade in a 5-grade system such as GIA’s would better be compared to the top two grades in a 10-grade system, such as AGS’s. The agreement between them is even better on that basis.

This is a good point Mike. I would make one correction though. AGS is actually an 11 grade system instead of a 10.

Peace,

Rhino..

The point of Michael''s IS NOT A GOOD ANALOGY, in my opinion, as the example posted in this thread of a theoretical purely symmetric GIA EX that would get an AGS 4 clearly illustrates. There will be AGS 0''s, 1''s, 2''s, 3''s 4''s, and maybe worse within the GIA EX range. And GIA might give an AGS 0 a grade of VG or G (especially in the case of painted girdles, where it appears GIA completely and arbitrarily discounts them).

Hey Marty,

I hear where you are coming from. I realize the fringes of the GIA Ex grade would make an AGS 4 however I do not want to arrive at rash conclusions before seeing the said stone. What I''m saying is that I don''t like to criticize any diamond until its in my hands and I''ve seen it personally. While the results of our last survey threw me for bit of a loop (I didn''t think for one moment that consumers were going to pick how they did before that type of exam), I am still skeptical of the steeper combination which is why I am seeking such a stone out. Once we acquire such a stone, I will have then at least found the threshold for *appearance* that makes it into the GIA top grade. I may or may not agree with the appearance and may not personally be what I prefer, but the opinion that counts more to me ... even more than you guys (as much as I respet the opinions of my peers) is that of the consumer and it is their input I will be garnering once I acquire it.

Date: 3/19/2006 3:36:35 PM
Author: adamasgem

On the opposite side, I AGREE WITH GIA, for what it is worth, that VG and EX polish should not exclude a stone from a an AGS 0 overall cut grade, as is AGS''s current practice, I believe.

Are my ears/eyes deceiving me?

hehe

Date: 3/19/2006 3:36:35 PM
Author: adamasgem

There is NOT a linear uniform distribution of grades in EITHER SYSTEM, given the table/crown/grdle/pavilion ( n space) parameter set (all other factors [stars, culet, lower girdles] being equal). And it also might be impossible to figure out given the constantly changing definitions and/or different of some words like ''thin to slightly thick''.

And the case of AGS basing grades on ''actual scans'' and GIA on averaged, rounded values further complicates differences.

At best we can look at what GIA and AGS would each give a theoretically symmetric stone set for the published parameter sets, like the ''illegal'' (from GIA''s perspective) comparisons I had posted (where someone else did the ''illegal work'' and I did the posting and color coding, as I disclosed) on an earlier thread.

John Quiote then did a volumetric count of these data on the FAQ, showing a 5 to 1 volumetric comparison between an AGS 0 and GIA EX. A much smaller 10 ring, with a small fraction of AGS''s 10 ring falling outside GIA''s EX ring.

Maybe ''acceptable'' for the masses, but subject to vast differences in prices/discounts in the trade, most (if any) of which will not be passed to the consumer. It it my fear, based on almost 100% certainty, that GIA EX''s will be passed off as equivilant in cutting standards as AGS 0''s or even 1''s.

Which is why, as always, the consumer must do their homework as well as the gemologist. While experts may agree/disagree on certain issues in each of the cut grading systems, the consumer who doesn''t feel like looking into these things is safest getting a stone that falls into the top grade of both. My suggestion of course, if there are disparaging opinions, would be to view both side by side and pick the stone they like best of course.

In my conversations with Al Gilbertson he had stated that one of the staff members on the cut research team REALLY liked one of the Grade 3''s that were a shallow/shallow. I couldn''t help but think of Garry.

And after reexaming some of our older stock stones of the like, I totally understand how one could prefer that. The dudes on both cut teams (GIA & AGS) are hoping that their research encourages more people to *look* at diamonds to better understand what their personal preferences really are. Who knows ... ones personal preference may be for an AGS 4?!?

Peace,

 

[adamasgem]

Date: 3/19/2006 3:44:42 PM
Author: tarssarb

So if you have a ags000 from mid feb 2006 ad it exhibits painting (girdle ~1-4%) and matching lightscope, does that mean it is to a degree that the performance isn''t significantly different from a standard girdle ags000 from mid feb 2006? What a bummer this thread just came out!

Hey tasssarb, someone pointed out your possible credentials via a play on your name.
You can contact me privately, through the email on my website. I like to have an idea of the
qualifications of those that post, as the technicallity of the response can be specifically directed.

Sometimes I find it difficult to describe things to people that have to be told the same thing ten times and still not understand

Thanks. PS. Your identity will remain annonomous on PS.

 

[Rhino]

Date: 3/19/2006 7:21:09 PM
Author: adamasgem

Date: 3/19/2006 7:03:24 PM
Author: Rhino

Date: 3/19/2006 2:25:43 PM
Author: adamasgem

Not a problem Marty. Garry has suggested .gem files. What is your preference?

Thanks RRhino,
I guess gem files will have to do, as regular dms files may be too large for posting on PS with the 100K limit. DMC''s would be better, as it seems that the angles are not readily available when you use DiamondCalc and import gem files.

I tried using gem files with GemAdviser but it expired so I have to download a new version. I don''t know whetehr it wil give the min maxes,ect I was lokkking for, like the full blown dmc helium files..

For the edification of all here are gem files. Marty ... you can drag these files into the DiamCalc and they''ll open up in there. If you''d like the more detailed .dmc files as generated through a Helium scan I''ll forward them to you via email.

So nobody is confused the next two files I''m going to post are from our survey of a GIA Ex 35.1 crown angle 41.2 pavilion angle. The diamond is a 1.01ct D VS2 and Pete has confirmed with me that the stone would be an AGS 1 in their current system.

 

[Rhino]

Here's the painted stone from our survey in the other thread. Sergey has told me this stone is between 1 and 2 clicks, not as bad. I am still learning the "click" thing but Sergey has made it clear to me that 2 clicks (another stones file I had sent him of a 1.18ct K VS2 was too much painting) which we are both in agreement on. My personal goal is to determine (whether GIA considers it Ex or not is to determine how much or little painting can be done before it impacts anything).

Perhaps a photo of each of these painted stones would make an interesting comparison? One with 2 clicks and one in between 1 and 2?

Peace,

 

[adamasgem]

Date: 3/19/2006 5:49:05 PM
Author: oldminer
Years ago, 1986-88, when I made up the initial AGA Cut Class grades the 1A was narrow and after a long time I conceded it was too narrow to be commercially viable. It was strict to Tolkowsky and stones in that narrow range are truly great stones. Yes they did.. and you can trace that effective methodology, for all its minor faults, backh to the starting of the recut weight theory of many moons ago, when I first toook the GIA course, when there was meat in them. Happily, I am told that some aspects have improved since the downturn of the early 90''s

I know now that 1A didn''t cover all the possibly fine stones, but I had an unrealsitstic view of the market and the way the trade views presentation of the facts.I don''t think it was unrealistic at all. It was one of the things that drove better cutting, based on what could be done at the time, and, along with contributions and understanding of what made better cutting and better performing diamonds by the owrlds top cutters through experimatation led to the "ideal cut", It was of considerable importance. Don''t short change it.

I never made it more broad, but stuck to the basic truth that it revealed about where the best were known to be.

And it served us well, and made sense. Did you notice the overlay of the original GIA cut classes on what I had posted.

Now, maybe AGS has taken the high road and will find out what I learned quite a few years back. Too narrow a definition of ''the best'' won''t win you any friends in the marketing plans of major sellers. Yes, I think that wasn''t the intent. It was not meant to pander to the trade.

On the other hand, the GIA looks as if it decided to finally give the much requested cut information, but make the top grade broad enough to cover way more diamonds than what ought to be accepted as ''the best''. I agree based on my experiance.

The ones AGS has chosen and the ones GIA and AGS hold in common might make an excellent compromise if they are in a continuous set of parameters. That certainly seems like logical advice for the consumer, it is called majority logic.

Leaving off the rest of the GIA stones might allow all the world to proceed to create some sort of agreed ''standard'' for the time being.Exactly

It seems so unproductive to criticize without searching for the common ground solution that could help us all carry on. In time, we''ll do better still.It will take some time, I know AGS will eventually be looking at things I discussed with them, and maybe GIA will tighten their "definitions", but I somehow doubt it.

Half the problem is one organization seems to have put too much "weight" on "consumer and trade preferences", probably because of the resources needed to look at it from a purely technical mode and present the pros and cons of each side. That is the problem with adopting "standards" that will fit world wide. It seems more about selling paper, and pleasing the "merchandising" audiance.

Perhaps, you might post the historical evolution of the round Charts on a knowledge base article.

 

[Garry H (Cut Nut)]

Michael you are very handsome

Date: 3/19/2006 1:00:09 PM
Author: Serg


I do not like lost time in empty discussion more. We need more hard facts.

I am ready invest 5.000-10.000$ to small MSS
M = master S=stone S= study
Put me down for $5,000 Sergey - I guess we will get some or most of that money back after we sell the diamonds - and we could ask the labs to refund their fees perhaps - most of the stones would never be saleable with those reports.



Part 1 GIA Excellent
1) Crown is fix 34, 34.5 or 35 within .2 degrees would be good. Table should be between 55 and 58% ???
2) Pavilion step 0.2 degree. 40.6, 41, 41.2, 41.4, 41.6

Part 2
click Painted crown. Same crown Pav 40.6, Pav 40.4( I will try receive just Good here) why so shallow? Painting makes a stone appear more shallow.




Part 3



Some GIA very good ( 3-4 diamonds)
40.4 , 40.8 + some other diamonds I would like to start at 40.0 then 40.2





All ideal symmetry. Clarity an color are good for sells. Diameter 5-6 mm The bigger the better - say 3/4ct - in a perfect world the stones are all either the same diameter and different weights - but all in the same weight / price grid - or the same diameter but different weights. This is what i tried to do with my Diamond Dock study.

I will send all diamonds to GIA and AGS.

This MSS will available for different appraisers and consumer research at least 3 months.

Welcome to invest Money, Time, Ideas, service. Hope Garry will help.

Our study will open during all steps.

Re Gem files vs Diamcalc - they are exactly the same file - so if you save one or the other - you can change the suffix (on the end) and change them around.
DiamCalc from Helium is a 330kb sized file - too large to post on Prricescope - the extra data makes vieing many pages of data avaliable in DiamCalc (or gem adviser I think).

You can save a big helium DiamCalc - open it - save it as a Gem file with the Small file option - then:

You can make these files back into small gem or resave a small DiamCalc version

Wink I suggested saving in Gem file format so people who do not have full diamCalc licences can view the files

 

[adamasgem]

Date: 3/19/2006 7:34:15 PM
Author: Rhino

.

Date: 3/19/2006 3:36:35 PM
Author: adamasgem

On the opposite side, I AGREE WITH GIA, for what it is worth, that VG and EX polish should not exclude a stone from a an AGS 0 overall cut grade, as is AGS''s current practice, I believe.

Are my ears/eyes deceiving me?

hehe

Nope you heard right, just like I have pointed out to Sergey ans AGSL that picking out one tilt can give potentially misleading results also.



Which is why, as always, the consumer must do their homework as well as the gemologist. While experts may agree/disagree on certain issues in each of the cut grading systems, the consumer who doesn''t feel like looking into these things is safest getting a stone that falls into the top grade of both. My suggestion of course, if there are disparaging opinions, would be to view both side by side and pick the stone they like best of course.

I agree

 

[RockDoc]

What we potentially are headed for.


As those of us who either prefer or not prefer the results in a diamond''s appearance with painting, there will eventually come in time an even narrower grading system which will or should inform consumers as to whether the stone is painted, or not AND to what extent that would be negative or positive, to the greatest number of trade people as well as consumers.

But many times what is paramount to buyers for resale as well as consumer purchasers is how all this is going to reconcile in the pricing of stones.

Those who particpate in searching out the ultimate answers, are in many cases "hair-splitting" and possibly creating
Frankenstein like customers, who believe their is an ultimate cut quality stone, when in fact most of the stones we''re discussing are vastly superior to what is sold out in the marketplace en masse.

To the expert eye, evaluating the hair splits between stones is attainable, but for the consumer''s inexperienced eye, it really isn''t and in many of the people that I''ve shown and taught appearance qualities to, a lot of times, their analysis is price/cost driven when in their opinion the differences are minor (to them) even if they are more siginficant the recognizable to us.

Experts and experienced members of the trade and labs, are not only interested in finding the UTOPIA cut grade diamond, but the reason of the WHY we see the differences in what we do.

But it stands to reason that as we define the average from the best of the very best and the ultimate, that the price and cost will play a strong part as a result.

Rockdoc

 

[adamasgem]

Date: 3/19/2006 6:37:31 PM
Author: Rhino


PS: I wasn''t aware we could post .dmc files here!!! How excellent!

Yup, but watch it, there is a size limitation of 100K bytes, and some dmc files are much larger (300K+), unfortunately.

An even if it gets rejected for size, it seem to take up the file name as previously posted. I''ve had that problem with jpegs, sort of a quirk I think.

 

[JohnQuixote]

Date: 3/19/2006 7:34:15 PM
Author: Rhino

In my conversations with Al Gilbertson he had stated that one of the staff members on the cut research team REALLY liked one of the Grade 3''s that were a shallow/shallow. I couldn''t help but think of Garry.

And after reexaming some of our older stock stones of the like, I totally understand how one could prefer that. The dudes on both cut teams (GIA & AGS) are hoping that their research encourages more people to *look* at diamonds to better understand what their personal preferences really are. Who knows ... ones personal preference may be for an AGS 4?!?

Agreed. There are combinations of steep a bit outside of AGS'' paradigms or shallow a bit outside GIA''s paradigms that will appeal to people. I think we''re fine with that. But don''t you agree that most people would not prefer a 1.28 with the face-up spread of a 1.16 (for example)...if they were aware that this was the case?

 

[Garry H (Cut Nut)]

An interesting thought:

I was surprised that a retailer would use a typical dealers lighting to judge the cut quality of a diamond. Rhino uses the Geisen twin fluoro for example (I think you wrote that rhino?).

When ever i have been buying in dealers environs - I never make decisions in that lighting & I am asking myself why? (perhaps instinctively - perhaps because it disagreed with my Ideal-scope / FS observations - I dont know when or why I stopped or changed).

Sergey has shown now that this is really bad, and shown why. I always knew that looking at inclusions with backlight thru the diamond was bad news for cut grading - even though I have seen countless thousands of merchants, graders and appraiser students do it. And a typical dealer has a big white pad on the desk just to make the environment worse.

I think back to some of my debates with Brad and Jan - and it is clear now why they believe what they believe - I thought at the time that they were simply allowing back light to enter the pavilion because the way they took their photo''s - but actually they too probably use strong desk liights!!!

How do we get the trade to change to using consumer type lighting?
How do we stop this stoopid usage of LED lamps sitting on desks so people can see the fire in a diamond?

 

[JohnQuixote]

Date: 3/19/2006 8:11:41 PM
Author: RockDoc
What we potentially are headed for.


As those of us who either prefer or not prefer the results in a diamond''s appearance with painting, there will eventually come in time an even narrower grading system which will or should inform consumers as to whether the stone is painted, or not AND to what extent that would be negative or positive, to the greatest number of trade people as well as consumers.

But many times what is paramount to buyers for resale as well as consumer purchasers is how all this is going to reconcile in the pricing of stones.

Those who particpate in searching out the ultimate answers, are in many cases ''hair-splitting'' and possibly creating
Frankenstein like customers, who believe their is an ultimate cut quality stone, when in fact most of the stones we''re discussing are vastly superior to what is sold out in the marketplace en masse.

To the expert eye, evaluating the hair splits between stones is attainable, but for the consumer''s inexperienced eye, it really isn''t and in many of the people that I''ve shown and taught appearance qualities to, a lot of times, their analysis is price/cost driven when in their opinion the differences are minor (to them) even if they are more siginficant the recognizable to us.

Experts and experienced members of the trade and labs, are not only interested in finding the UTOPIA cut grade diamond, but the reason of the WHY we see the differences in what we do.

But it stands to reason that as we define the average from the best of the very best and the ultimate, that the price and cost will play a strong part as a result.

Rockdoc

Well put. I think it was Michael who first pointed out that there are 2 discussions happening simultaneously in these threads:

1. The broad upper range of steep/deep in GIA, which could/will impact the average consumer. Some vendors will screen such diamonds but others may not, leaving consumers unprotected.

2. The brillianteering question, which is indeed hair-splitting, subject to taste and not easily defined. This revolves around a niche market most consumers will never be exposed to.

 

[adamasgem]

Date: 3/19/2006 7:45:31 PM
Author: Rhino

For the edification of all here are gem files. Marty ... you can drag these files into the DiamCalc and they''ll open up in there. If you''d like the more detailed .dmc files as generated through a Helium scan I''ll forward them to you via email.

So nobody is confused the next two files I''m going to post are from our survey of a GIA Ex 35.1 crown angle 41.2 pavilion angle. The diamond is a 1.01ct D VS2 and Pete has confirmed with me that the stone would be an AGS 1 in their current system.

Thanks Rhino for the two scans..

 

[strmrdr]

Hey I resent being called "Frankenstein"
There is a ultimate diamond cut.. the tech just cant make or measure it yet :}
Till then the ones with the least compromises will have to do :}

 

[dhog]

Date: 3/19/2006 8:24:23 PM
Author: Garry H (Cut Nut)
An interesting thought:


I was surprised that a retailer would use a typical dealers lighting to judge the cut quality of a diamond. Rhino uses the Geisen twin fluoro for example (I think you wrote that rhino?).


When ever i have been buying in dealers environs - I never make decisions in that lighting & I am asking myself why? (perhaps instinctively - perhaps because it disagreed with my Ideal-scope / FS observations - I dont know when or why I stopped or changed).



Sergey has shown now that this is really bad, and shown why. I always knew that looking at inclusions with backlight thru the diamond was bad news for cut grading - even though I have seen countless thousands of merchants, graders and appraiser students do it. And a typical dealer has a big white pad on the desk just to make the environment worse.


I think back to some of my debates with Brad and Jan - and it is clear now why they believe what they believe - I thought at the time that they were simply allowing back light to enter the pavilion because the way they took their photo''s - but actually they too probably use strong desk liights!!!


How do we get the trade to change to using consumer type lighting?

How do we stop this stoopid usage of LED lamps sitting on desks so people can see the fire in a diamond?

and the birth of the diamond dock,