GIA Ex: The Consumers Perspective and the Technologies

[michaelgem]

On the issue of spread, which is the diamond''s apparant size ( diameter for a given weight.)

re: But would you pay top dollar for Jonathan’s example steep/deep stone?

May be I will pay 95-100% I see only one objective reason for discount now. It is spread. Sergey Sivovolenko

The only valid reason to down grade it is if these proportions combined with girdle thickness and table size result in a cut that does not “spread” sufficiently. Spread (apparent size) is another criteria for Ideal or Excellent, separate from optical performance. Michael Cowing

Michael Cowing

www.acagemlab.com

 

[michaelgem]

re: But if you looked at a steep deep from 14 to 15 inches 350 cm - this is the leakage you would see in a GIA Excellent AGS 5 stone seen with 5 degrees of tilt.

But your brain could not see leakage in Jonathan’s T57P41.2Cr34.5=AGS4,
The right eye will see a bright zone on the left side and a dark zone (leakage in IS) on the right side in the table in normal light conditions.
The left eye will see a bright zone on the right side and a dark zone (leakage in IS) on the left side in the table in normal light conditions.
If the bright zones are brighter than the level of eye adaptation (as they usually are), your brain cannot see any dark ring in the table. Sergey Sivovolenko

Sergey makes an important point about stereovision and the psychophysics of how the brain combines left and right eye imagery.

There is another simple reason why slightly steep/deep diamonds will often be preferred even if you put a patch over one eye or are looking closely at the diamond with your dominant eye.

Michael Cowing

www.acagemlab.com

 

[adamasgem]

OK, While I was surprised at Rhinos test results, I guess I shouldn’t have been surprised.

1) The only valid consumer comparison test, with the INTERPRETATION being the relative merits of a painted girdle stone, especially when ONLY two stones are being compared, SHOULD REQUIRE that they are of the same size, have the SAME optical/physical symmetry, with the SAME facet angles and lengths with the ONLY difference being the angles or indexing of the crown breaks. ADDITIONALLY, they should be of the same color grade and diamond type, ie spectral absorption characteristics. Otherwise, interpretation of consumer preferences as an indictment of painted girdles, is pure bulls**t. Sorry Rhino.

2) The AGS cut grade methodology is entirely different than GIA’s, in that AGS’s is based on the RAY TRACING of the actual stone and GIA’s is based on AVERAGED, ROUNDED, IDEALIZED stones with both fixed modeled glare and “consumer and trade biased” preferences under unknown conditions and glare thrown in for good measure, such that the “experiments” can be reproduced, sort of like GIA “cold fusion”.

3) What has NEVER been stated is what is the miss-mash of the GIA test stones relative to distribution of color grades. While the first GIA article in 1998 was based on theoretical stones, in their fire article of 2002, they introduced the 27 real stones, the measurements of which of which were changed when they published their 2004 article. WE KNOW NOTHING about these stones other than the AVERAGES from which we can hopefully deduce some relative “goodness factors” which MAY OR MAY NOT correlate with ANY observational data BECAUSE WE KNOW NOTHING ABOUT THE SYMMETRY of these test stones.

4) An exact definition of the stone is important because it effects the pathlength and internal absorption in the stone defined by Beer’s Law (look it up Rhino). When we ray trace with an idealized diamond (no absorption) the average number of facet interactions until all (99.9%) of the light is lost is significantly different from stone to stone (see graph for average pathlengths and interactions for the original GIA hemispherical lighting and colorless diamond) , and WILL CHANGE RADICALLY when we factor internal absorption into the mix, based on the theoretical studies I have done using actual diamond absorption spectra from flat plates of synthetic type IIa diamond where I have a reference pathlength to use. The average pathlength will also vary with the lighting source used. DiamondCalc also has the ability to do this if you know the normalized 1mm absorption spectra to use. EVEN A D COLOR DIAMOND IS NOT PERFECTLY TRANSPARENT, otherwise we wouldn’t have color grades or see subtle color differences in the faceup position..

5) AS I HAVE REPEATABLY SAID ON PriceScope and elsewhere, ENVIRIONMENT will change your perspective of the stone. What appears disingenuous is that GIA says they define the modeling basis of their metrics one way and then produces a “sales tool” which has an entirely different lighting environment, and there is an apparent theoretical dichotomy between the two. We are asked to accept their GIA “results” based on blind faith, oh yah, enough said about that. You all know where I stand on that.

6) Getting back to Rhinos tests, I resurrected summaries of SAS2000 forward 3D raytrace modeling I had done to check on GIA’s results a year ago. (Somewhere on Pricescope is a long technical thread which was mainly between Sergey and I which defined the different SYMMETRICAL models I used for these data, all extracted from the GIA published data.). In all cases I applied the original GIA Weighted Light Return Cosine squared function to all data (the concept of which I technically agreed with, and still do) and then normalized to the Tolkowsky model that GIA used in their original technical study and applied the same constraints. The lower right graph shows my comparison with the published GIA data based on a UNIFORM INTENSITY HEMISPHERE WITH A BLACK HOLE AT THE GIRDLE PLANE.. (What has also been done is ASET modeling for these stones for a complete range of tilts, a sample of which I put up on another PS thread, but that again is a subject for another thread). While I don’t expect perfect correlation in MonteCarlo modeling, a couple of points suggest strongly to me, that something might be wrong in the GIA published data. GIA REPEATABLY refused to admit to any errata in their published data and I and another had double and triple checked my input data relative to what GIA published. I then modeled the WLR for a 18 inch fluorescent tube (cool white) with a physically distance attenuated intensity (no head obscuration) and a uniform intensity parallel ray front (no head obscuration) under Daylight 6500K as well as the established Blue sky (with 9 degree head obscuration) and Cloud covered sky hemispherical attenuation models (no head obscuration). As to “head obscuration”, the head is not a pure absorber, it REFLECTS, from 20 to 60 percent, and again I have published data to substantiate this from texts on PriceScope. Also there is NO GLARE in these results, and I agree with GIA’s ORIGINAL position on this.

7) I leave it to the reader to make their own interpretations or misinterpretation, but AS I HAVE SAID BEFORE, my interpretation is that IT IS ALL ABOUT ENVIRIONMENT. (Note that the scales are different from graph to graph because of the min max in the data sets.)

EDIT: The model definition used may be found on this PS page
https://www.pricescope.com/community/threads/ags-new-cut-grade-system-early-2005.19268/page-11

 

[adamasgem]

Here are the facet interactions and pathelength in terms of diameters for the GIA hemispherical model.

 

[michaelgem]

There is another simple reason why slightly steep/deep diamonds will often be preferred even if you put a patch over one eye or are looking closely at the diamond with your dominant eye.

Slightly steep/deep diamond’s like 41.2/35 avoid to a greater extent the observer head obstruction that produces darkness, firstly in the mains and then in other areas of the diamond. This is in comparison to Tolkowsky reference diamond angles of 40.75/34.5. At the same time 41.2/35 does not incur significant leakage in the "middle ring" of reflections inside the table.

It is a matter of which negative effect is most dominant to the eyes of the observer. The results of observational testing by GIA, and now Jonathan, suggest that in spite of the middle ring light leakage, a diamond like 41.2/35 that better avoids observer head obstruction is preferred over 40.75/34.5.

Michael Cowing

www.acagemlab.com

 

[Serg]

re:The main technical criticisms against the new GIA-system are basically two-fold. One is that the top-grade of the 5-layer-system is too broad. This point is, I believe, not the topic of this thread. Can we therefore not confuse matters by avoiding any comment on that?

The second criticism is the ''apparent'' automatic downgrading of all painted and digged lower-facets by GIA, be they intentional or unintentional, patterned or non-patterned. Here we have the case where a non-painted GIA-EX with non-super-ideal proportions is prefered over an AGS-0 with super-ideal proportions, but with painting. Interesting, indeed.


No. Main point: GIA DD light scheme is not adequate for consumer light condition.
It is reason Why GIA cut grade is wrong( Good diamond can receive wrong grade( First type mistake), bad diamond can receive good grade( Second type mistake))

AGS cut grade system has mistake too. but AGS Second type mistake is less and AGS ready to fix mistakes in future( AGS use rejection grading system. Such system allow add new rejection rules easily . GIA can not fix mistake easily .GIA system is not rejection system( except penalty for type girdle,...)

I think Second type mistake is much more danger than First type mistake

 

[adamasgem]

By the way, I wish Rhino would post dmc file for both stones as well as scans of the GIA and AGS reports... Color, clarity, fluorescence, as well as strain all effect perception tests

 

[tarssarb]

Adams:
"An exact definition of the stone is important because it effects the pathlength and internal absorption in the stone defined by Beer’s Law (look it up Rhino). When we ray trace with an idealized diamond (no absorption) the average number of facet interactions until all (99.9%) of the light is lost is significantly different from stone to stone (see graph for average pathlengths and interactions for the original GIA hemispherical lighting and colorless diamond) , and WILL CHANGE RADICALLY when we factor internal absorption into the mix, based on the theoretical studies I have done using actual diamond absorption spectra from flat plates of synthetic type IIa diamond where I have a reference pathlength to use. The average pathlength will also vary with the lighting source used. DiamondCalc also has the ability to do this if you know the normalized 1mm absorption spectra to use. EVEN A D COLOR DIAMOND IS NOT PERFECTLY TRANSPARENT, otherwise we wouldn’t have color grades or see subtle color differences in the faceup position.."


Are you saying that a diamond with great symmetry will keep light internal (from internal reflections (snell's law)) longer and thus have a longer pathlength and thus more adsorption (beer's law) and thus a darker appearance? Also you said lightsource may change pathlength but it seems to me it would change emissivity (ie emiss is func of wavelength). Regardless, wouldn't the only light of interest be the visible light and for a colorless stone would emissivity/pathlength play a major role in human perception?

If I digest your points in my head it would seem possible to me that a stone could exist of great optical design that light would mainly be able to escape from a cycle of numerous internal reflections in designated areas. Those areas of light return may be of larger intensity while no light emerged from the other areas of the stone top. That could be a good thing but appear to be a bad thing (ie in the brilliance scope thread I posted for 8star, the light only comes out to the overhead camera from the arrow and shaft regions and seems to lack a lot of random white dots that a maxed out brilliance scope shows). Ie, the diamond body appears darker between the areas of light return?

 

[BrianTheCutter]

I don’t think you can call any situation where money could change hands a ‘research’ environment.

But, if such in-store comparisons are valid, we have numbers to offer as well. We have performed several thousand consumer comparisons between premium painted and traditional diamonds in actual daylight, filtered daylight and LED environments. They disagree with Rhino's results. Maybe the number of test subjects is limited in his case. We have hundreds of similar superideals of both types of brillianteering at our disposal at any time - in all sizes and categories. They are compared by consumers on a daily basis. As for correlation, these consumer observations have agreed with further real world observations away from our offices, over many years. So, if you count this as valid, please add the many thousands of New Line (and Eightstar) owners who selected their diamonds over other ideal, superideal, 60/60 and steep/deeps. These people did intense research before purchase. They continue the research every day of their lives.

We should probably differentiate between casual comparisons, which we have been conducting since 2000, and a true research environment which implies unbiased feedback from observers who are not shoppers/buyers, performed on neutral ground.

Another important point is that meaningful control for observation of painted vs traditional brillianteering will require identical diamonds (in c/c/c, physical and optical symmetry) the only difference between them being that of brillianteering.

Perhaps this thread could be “GIA EX: The perspective of some people in my store.”

 

[strmrdr]

Date: 3/13/2006 12:46:19 PM
Author: adamasgem
By the way, I wish Rhino would post dmc file for both stones as well as scans of the GIA and AGS reports... Color, clarity, fluorescence, as well as strain all effect perception tests

sunday and monday are his days off.
tomorrow when he is back to the store will liklely be the earliest for more info.

 

[michaelgem]

Darkness due to head obstruction or absence of light from angles near the observer's "line-of-sight"

My recent observation:

It is a matter of which negative effect is most dominant to the eyes of the observer. The results of observational testing by GIA, and now Jonathan, suggest that in spite of the middle ring light leakage, a diamond like 41.2/35 that better avoids observer head obstruction is preferred over 40.75/34.5.

When we talk about observer head obstruction causing darkness in a diamond, it is often a point of confusion. We are referring to negative effects caused by the relative absence of light at angles close to the line-of-sight between the viewer’s eye and the diamond.

The reason we call it head obstruction is that the observer’s head is always present, obstructing light from angles near the line-of-sight. This occurs to varying degrees depending on head size and viewing distance.

You can see in this photograph that if you are outside under open sky, and looking down at the diamond, your head is the obstructer of illumination near the line-of-sight.

It is key to note that the same darkness will result when there is an absence of illumination in the vicinity of the line-of-sight even when the absence is due to reasons other than viewer obstruction.

If you are using a desk lamp or DiamondDock for illumination, and you tilt the diamond back toward your eyes, the main illumination may be from angles around 45 degrees and not in the vicinity of your line-of-sight.

Comparing diamond’s in an environment where there is absence of illumination near the observer ‘s line-of-sight is a factor in the preference for the slightly steep/deep.

Michael Cowing

www.acagemlab.com

 

[adamasgem]

Date: 3/13/2006 1:06:38 PM
Author: tarssarb

Adams:
''An exact definition of the stone is important because it effects the pathlength and internal absorption in the stone defined by Beer’s Law (look it up Rhino). When we ray trace with an idealized diamond (no absorption) the average number of facet interactions until all (99.9%) of the light is lost is significantly different from stone to stone (see graph for average pathlengths and interactions for the original GIA hemispherical lighting and colorless diamond) , and WILL CHANGE RADICALLY when we factor internal absorption into the mix, based on the theoretical studies I have done using actual diamond absorption spectra from flat plates of synthetic type IIa diamond where I have a reference pathlength to use. The average pathlength will also vary with the lighting source used. DiamondCalc also has the ability to do this if you know the normalized 1mm absorption spectra to use. EVEN A D COLOR DIAMOND IS NOT PERFECTLY TRANSPARENT, otherwise we wouldn’t have color grades or see subtle color differences in the faceup position..''


Are you saying that a diamond with great symmetry will keep light internal (from internal reflections (snell''s law)) longer and thus have a longer pathlength and thus more adsorption (beer''s law) and thus a darker appearance?

No , I believe the effect of better optical symmetry is just the opposite in general, although optical symmetry provides more contrast, so that areas like the arrows may appear darker. I''ve seen one K color 8* that I thought was an H or better.


Also you said lightsource may change pathlength but it seems to me it would change emissivity (ie emiss is func of wavelength). Regardless, wouldn''t the only light of interest be the visible light and for a colorless stone would emissivity/pathlength play a major role in human perception?

Emmisivity (blue fluorescence) makes the stone appear whiter by emitting in the blue, the wavelengths of which have the highest relative absorption in a cape stone.


If I digest your points in my head it would seem possible to me that a stone could exist of great optical symmetry that light would mainly be able to escape from a cycle of numerous internal reflections in designated areas. Those areas of light return may be of larger intensity while no light emerged from the other areas of the stone top. That could be a good thing but appear to be a bad thing (ie in the brilliance scope thread I posted for 8star, the light only comes out to the overhead camera from the arrow and shaft regions and seems to lack a lot of random white dots that a maxed out brilliance scope shows). Ie, the diamond body appears darker between the areas of light return? Contrast

Additionally the Brilliance scope backlights the diamond, but from what I have seen, and have been told, the results correlate well with observation, but the pictures may be a little confusing. At least they were to me with the VERY limited experiance I have had with it.

 

[adamasgem]

Date: 3/13/2006 1:18:31 PM
Author: michaelgem


Comparing diamond’s in an environment where there is absence of illumination near the observer ‘s line-of-sight is a factor in the preference for the slightly steep/deep.
I agree 100%.. Interestingly, the list of GIA hemispheres used in their studies, and their brightness metric large head mostly have face up viewpoints while as I remember, there were a limited numer of controled offset viewpoint tests. But the head also reflects... Hard to control in a consumer sales envirionment..

Maybe if everyone were made to use your idea of a red (black) paper bag over ones head while viewing diamonds the results would agree better with their models..

 

[RockDoc]

RE: THE RED BAG.....which I''ve suggested for years now.


Gotta remember to make holes for the eyes.

I like RED better than black as with the black it is hard to tell shadowing from the angle of the stone or light, and the red sort of minimizes the additional shadowing that might not be obstruction at all.

This I think is particularly and notably important, when viewing the stone in the tilted mode.


Rockdoc


Rockdoc

 

[adamasgem]

Date: 3/13/2006 1:45:02 PM
Author: RockDoc
RE: THE RED BAG.....which I've suggested for years now.


Gotta remember to make holes for the eyes. <G>

I like RED better than black as with the black it is hard to tell shadowing from the angle of the stone or light, and the red sort of minimizes the additional shadowing that might not be obstruction at all.

This I think is particularly and notably important, when viewing the stone in the tilted mode.

Better watch out now, someone watching this thread will take the red/black bag idea, change it to a proprietary patented non neutral color(maybe green for money), steal my comments about sunglasses or poloroid film to cut out the glare, and patent the whole thing and sell it to all those who buy the $1.6K DD at an addtional $1K apiece (because you really need it to understand our system), but that would defeat the whole apparent purpose of the DD (obsfucation)

 

[strmrdr]

Date: 3/13/2006 1:12:09 PM
Author: BrianTheCutter
I don’t think you can call any situation where money could change hands a ‘research’ environment.



But, if such in-store comparisons are valid, we have numbers to offer as well. We have performed several thousand consumer comparisons between premium painted and traditional diamonds in actual daylight, filtered daylight and LED environments. They disagree with Rhino's results. Maybe the number of test subjects is limited in his case. We have hundreds of similar superideals of both types of brillianteering at our disposal at any time - in all sizes and categories. They are compared by consumers on a daily basis. As for correlation, these consumer observations have agreed with further real world observations away from our offices, over many years. So, if you count this as valid, please add the many thousands of New Line (and Eightstar) owners who selected their diamonds over other ideal, superideal, 60/60 and steep/deeps. These people did intense research before purchase. They continue the research every day of their lives.


We should probably differentiate between casual comparisons, which we have been conducting since 2000, and a true research environment which implies unbiased feedback from observers who are not shoppers/buyers, performed on neutral ground.



Another important point is that meaningful control for observation of painted vs traditional brillianteering will require identical diamonds (in c/c/c, physical and optical symmetry) the only difference between them being that of brillianteering.



Perhaps this thread could be “GIA EX: The perspective of some people in my store.”

I would love to see a truly independent study done with consumers only.
The traditional way to do this is hire an independent testing agency to do it.
Sometimes you can find a college to do it for free also if its something they find interesting.
Establishing the protocol would be the big issue.
Maybe later if someone else don't do so Ill start a thread on it for a game of what if.

edit: I wanted to make it 100% clear that I believe that both Rhino and Brian are being 100% truthful about the consumer observations they are talking about in this thread.

 

[elmo]

Date: 3/13/2006 3:05:59 PM
Author: strmrdr
I would love to see a truly independent study done with consumers only.

The consumers need to be selected as if for a jury I think - something from the GIA technical FAQ quoted on the first page of this thread that struck me was this:

Those who did not market this type of diamond chose it as best about as often as they chose other diamonds we have placed in the top grade categories. It appears that these types of diamond could be likened to an “acquired taste” or “learned bias.”

The walk-ins at WF and GOG have already started to acquire taste, I think

.

 

[Garry H (Cut Nut)]

Date: 3/13/2006 1:12:09 PM
Author: BrianTheCutter

I don’t think you can call any situation where money could change hands a ‘research’ environment.

But, if such in-store comparisons are valid, we have numbers to offer as well. We have performed several thousand consumer comparisons between premium painted and traditional diamonds in actual daylight, filtered daylight and LED environments. They disagree with Rhino''s results. Maybe the number of test subjects is limited in his case. We have hundreds of similar superideals of both types of brillianteering at our disposal at any time - in all sizes and categories. They are compared by consumers on a daily basis. As for correlation, these consumer observations have agreed with further real world observations away from our offices, over many years. So, if you count this as valid, please add the many thousands of New Line (and Eightstar) owners who selected their diamonds over other ideal, superideal, 60/60 and steep/deeps. These people did intense research before purchase. They continue the research every day of their lives.

We should probably differentiate between casual comparisons, which we have been conducting since 2000, and a true research environment which implies unbiased feedback from observers who are not shoppers/buyers, performed on neutral ground.

Another important point is that meaningful control for observation of painted vs traditional brillianteering will require identical diamonds (in c/c/c, physical and optical symmetry) the only difference between them being that of brillianteering.

Perhaps this thread could be “GIA EX: The perspective of some people in my store.”

Brian the bigger variable would seem to be the lighting environment rather than the stones.

The fact that rhino''s results correlate with GIA''s result does nothing more than show that Rhino uses GIA Diamond Dock type lighting - Rhino you did mention you use a desk lamp of some sort?

As Sergey has shown in a previous thread - using fluoro lights in relatively close proximity to diamonds changes the entire result.

Michael as a camera and lighting expert you could probably explain the pupil / aperature size effects and how that changes our perception.

 

[dhog]

on the first page I said that 100% of the viewers would pick the GIA
stone.

This was based on research I did years ago involving light reflections in different light conditions in the manufacture and sales of fishing lures.(laugh if you want)what we came up
with was a contrast issue related directly to how humans see
light and dark spots on a reflective surface in multiply lighting
conditions.

Inhibitory reaction better known as(LATERAL INHIBITION NETWORK) is where we stopped our research.

I am not a light scientist or a diamond specialist and therefore
do not wish to pursue this but think that someone on here needs
to look at this and at least exclude it from the pack.


maybe all of this has already been explored and needs no
future reasoning, but I think others on here know what I am
talking about and will explore it further.

 

[adamasgem]

Date: 3/13/2006 9:17:26 PM
Author: dhog


on the first page I said that 100% of the viewers would pick the GIA
stone.

This was based on research I did years ago involving light reflections in different light conditions in the manufacture and sales of fishing lures.(laugh if you want)what we came up
with was a contrast issue related directly to how humans see
light and dark spots on a reflective surface in multiply lighting
conditions.

Inhibitory reaction better known as(LATERAL INHIBITION NETWORK) is where we stopped our research.

I am not a light scientist or a diamond specialist and therefore
do not wish to pursue this but think that someone on here needs
to look at this and at least exclude it from the pack.


maybe all of this has already been explored and needs no
future reasoning, but I think others on here know what I am
talking about and will explore it further.

Sergey has done more work in this sort of thing that I have, as I use foreward MonteCarlo and am interested in the numerical results, and DiamondCalc will do a photoreal representation which doesn't appear too bad if you have the "right" absorbance data. Sergey and his team and I have worked out and interface to enable me to geterate high resolution absorbance files for use in DiamondCalc, I guess which will be available in the next DC release from what I am told.

Modleing of the DC envirionment, is rather detailed, if anyone out there would like to loan me one for a few days I could obtain the spectral relfectance data on the paint they use.. I'll probably eventually build one that allows some things that GIA isn't doing, to enable some further studies, but be assured I will file the paper work for a design improvement patent before i tell anyone what I am doing, so the big org can't steal the ideas, and trust me I have first hand and documented knowledge from the late 1990's on what they do and have done, so I don't mind kicking a little sand in their face now and then. Again, I feel sorry for those who have to work in the circumstances they do at GIA's version of WorldCom.

 

[kenny]

I am certain Rhino is 110% truthful.
I never stated or meant to imply anthing else.
I only felt it is significant to acknowledge his close GIA association.

Rhino''s on my short list of sellers I''d trust to sell me fine rocks at great prices.

 

[michaelgem]

Dhog comments:

This was based on research I did years ago involving light reflections in different light conditions in the manufacture and sales of fishing lures.(laugh if you want)what we came up with was a contrast issue related directly to how humans see light and dark spots on a reflective surface in multiply lighting conditions. Inhibitory reaction better known as(LATERAL INHIBITION NETWORK) is where we stopped our research. Dhog

The psychophysics of human vision involves a mechanism called lateral inhibition. This mechanism results in a phenomenon known as simultaneous contrast. Among other things this natural contrast enhancement makes human vision great at edge detection.

With respect to reflections from diamonds, there is a natural enhancement through lateral inhibition of the contrast between adjacent reflections. It results in our attraction to diamond cuts that in typical viewing circumstance exhibit sharp and pleasing contrast qualities.

The community settled upon this contrast aspect of brilliance as a necessary augmentation of the old definition of brilliance as average brightness. I and others, including Octonus, GIA and AGS have addressed contrast brilliance and give it varying degrees of importance when judging the optical performance/beauty of a diamond cut.

I for one believe contrast brilliance is of great importance, since the old aspect of weighted light return brightness is as useful by itself as taking a light meter reading of a painting in order to judge its beauty.

Michael Cowing

www.acagemlab.com

 

[BrianTheCutter]

I see where Rhino moved statements I made in another thread to this one, rather than replying in the original discussion. The other thread was an overview and did not promote or disparage specific items, whereas this one does. Specific to this thread, I will gladly acknowledge that GIA EX includes some reasonable steep outside AGS0 tolerance. For that matter AGS0 includes reasonable shallow outside GIA EX (though far fewer).

The issues I raised are not about one lab versus another. They are about protecting consumers. From a standpoint of manufacture, GIA’s upper tolerances for steep/deep go too far. Factories will cut the heaviest GIA EX possible and some EX diamonds will appear smaller than they should, perform at reduced levels and/or entrap color. This does not protect consumers. I said all of this, in context, in the other thread.

My statements are factual. In his response here Rhino does not dispute the facts, but he asks if I have seen steep/deep cutting (Rhino are you joking to ask this?). Certainly my apprenticeship did not start with a piece of rough bound for premium make. I learned in South Africa, Amsterdam and Antwerp, polishing many configurations. My commitment to supersymmetry began after coming to America (do you realize supersymmetry has existed less than 25 years?). I am regularly overseas with our cutting sightholder, and most of my statement was written in Antwerp last month, where I see more diamonds per day than most store owners see in a year. Many of my colleagues also see this new ‘configuration cash cow,’ and fear its upstream impact and the trickle down to common consumers (mdx posted pertaining to this).

‘The Consumer’s Perspective’ is precisely what I wish to preserve. Consumer perspective is not just beginning Rhino, it is generations old: Consumer perspective is what caused Lazare Kaplan, Charles Tiffany, Harry Winston and Pierre Cartier to source diamonds near the same Tolkowsky proportions the world’s finest cutters still embrace (at the expense of weight). Consumer perspective created the concept of fine-make. Consumer perspective increased demand for optical symmetry. Consumer perspective built top brands, including premium painted superideals. Consumer perspective is why these diamonds command respect and value.

I fear consumer perspective is what was lost when trade members performed GIA’s observations, and diamonds with hidden weight/reduced performance (the very diamonds that profit the common trade members involved) were allowed in EX. Adjusting prior research and creating a DiamondDock to reverse-justify the trade observations doesn’t erase known physics and optical properties. It doesn’t fool a cutter either.

For those able to follow, Sergey and Marty can bring science on various points to the table. My perspective is fundamental – I learned by polishing diamonds from rough – but our conclusions are largely the same.

Date: 3/11/2006 3:05:19 PM
Author: Rhino


...if we are to level accusations against GIA for not grading optical symmetry, then to be fair you must also offer the same criticism against AGS. The truth is, neither lab found optical symmetry detrimental to diamond appearance in the grand scheme of cut grading.

Please read again. I did not criticize any lab for not grading OS. My comments regarded GIA’s lack of follow-through on their planned studies of symmetry deviation from 1998.

As for ‘the truth,’ make no presumptions about what has been done. My input has been sought, but I cannot elucidate which lab(s) or what was discussed due to non-disclosure agreements I have signed.

 

[valeria101]

Date: 3/13/2006 3:05:59 PM
Author: strmrdr

Date: 3/13/2006 1:12:09 PM
Author: BrianTheCutter

I don’t think you can call any situation where money could change hands a ‘research’ environment.

I would love to see a truly independent study done with consumers only.

If i am not mistakin'' the occasional survey paid for by news agencies not any party of the jewelry trade, about grading bias and what not... find alarming information that nevertheless has no bite. Why would a study about cut outside the trade have better sorts?

 

[strmrdr]

Date: 3/14/2006 9:42:41 AM
Author: valeria101

Date: 3/13/2006 3:05:59 PM

Author: strmrdr

Date: 3/13/2006 1:12:09 PM

Author: BrianTheCutter


I don’t think you can call any situation where money could change hands a ‘research’ environment.

I would love to see a truly independent study done with consumers only.

If i am not mistakin'' the occasional survey paid for by news agencies not any party of the jewelry trade, about grading bias and what not... find alarming information that nevertheless has no bite. Why would a study about cut outside the trade have better sorts?

Many/most of those studies are not well done and are mostly sound bites for the news show.
The have more influence than you think.
When people find out im into diamonds one of the first questions is usualy how do you avoid the rip off that such and such a news program / article talked about.
Followed by shock that people would actualy buy diamonds online.

 

[adamasgem]

From a cynic''s perspective, I would have to take the position that any comparisons done with the DiamondDock"grading" envirionment would have about the same validity as the new patent pending GIA cut grade computer...

Complete details on the technology and research behind this new development, just out of the GIA marketing department, can be found at http://8ball.ofb.net/ . I have been informed, though back door channels, that pricing will be right around the $999 pricepoint resistance of retailers, with significant wholesale discounts enabling even the underdog to include one with each CZ they sell.

 

[valeria101]

Date: 3/14/2006 12:31:28 PM
Author: strmrdr

Date: 3/14/2006 9:42:41 AM
Author: valeria101

Date: 3/13/2006 3:05:59 PM

Author: strmrdr

Date: 3/13/2006 1:12:09 PM

Author: BrianTheCutter



I don’t think you can call any situation where money could change hands a ‘research’ environment.

I would love to see a truly independent study done with consumers only.

If i am not mistakin'' the occasional survey paid for by news agencies not any party of the jewelry trade, about grading bias and what not... find alarming information that nevertheless has no bite.

The have more influence than you think.

Cool then. Pricescope did a survey on that. Why not on anything else

Good luck!

 

[tarssarb]

Rhino,

Can you post the brilliance scope pictures for the two stones (you just put the bars). Since the brilliance scope has just one camera and supposedly the steep/deep you picked looks good in stereo vision, I would be interested in seeing this limitation of gemex.

 

[adamasgem]

Flash News: Consumer Advisory: I have just heard rumors that unscrupulous knockoff artists (mostly overseas, like those exploiting the Rolex look) have had massive orders from mass merchandisers of diamonds (mostlymall retailers, but that is only heresay and not all inclusive) for slightly modified versions of the original GIA Cut Grade Computer Magic 8 Ball (a picture posted above on this thread), have been modifying the internal workings such that any question posed by the consumer regarding what they are seeing in the DiamondDock™ , would gives answers statistically more in favor of a GIA EX than in the original GIA patent pending design. I have been told by those in the know, that the original research leading to the development of the GIA Cut Grade Compter Magic 8 Ball concluded that slightly over 80% of diamonds (without painted break facets) would get a EX grade in GIA’s original patent pending Magic 8 Ball design, and these mass merchandisers had the unmitigated gall to hoodwink the consumer by producing knockoff devices that up these statistics to an unprecedented 90% (GIA 10% Rounding Down applied to this number). More to follow in this continually unfolding story, and how to recognize the misleading, if not fraudulent, knockoffs, and not be mislead.

I have been told that GIA has requested anti-aircraft batteries be installed by Homeland Insecurity around Carlsbad, such that they can take appropriate action themselves, lest any of the 100,000 planes already in the air with these knockoffs, land on the Left Coast. This will be in sole command by the Commander In Chief at Carlsbad. I wholeheartedly support this action by GIA.

If any of these knockoffs reach my desk, I will perform the necessary analyses and post pictures of these fallacious knockoffs. Unlike GIA case in Certifigate, however, I will name the guilty parties using these devices, if I can find out who they are, or unless they wish to remain anonymous, of course.

 

[Rhino]

Was able to break away for a bit and will do my best to answer all.

Date: 3/12/2006 6:28:40 PM
Author: valeria101
Not a fan of AGS more than GIA or anything.

Just wondering if these two stones weren''t good examples of the pitfalls each of the labs kindly allows by their grading procedure...


Here''s what I mean:

- It sounds like there isn''t such a thing as ''too dug/painted'' a RBC for AGS. Or too skinny/wide LGF... where at the extreme these need some excuse.

- It sounds like a bit of leakage here and there is not a bad thing for GIAs'' top grade as long as it makes commercial sense without clashing with good taste or some opinion poll.


Could it be that these two diamonds were examples of the two sorts of slack: one overly ''painted'' the other with a bit of leakage. And between two evils GIA''s turned out to be the least bad ?

Which sort of reminds me of THIS (i.e. the chart and comment about leakage)

I haven''t heard yet much discussion on this forum of elsewhere about where AGS may be wrong. Are they always right? What escapes their grid?

Ana you have a special talent of putting things into proper perspective. I have not made any concrete decisions to stock this type of GIA Ex at the present time but one thing I have personally concluded from this experiment ... I would rather stock a GIA Ex Steep/Deep than an AGS Ideal with painted girdles. It''s not to mean I might consider both, but seeing the ratio of consumer preference ...

My inventory over the years has always reflected what consumers preferred most after showing them all the options. As we would make these discoveries between super ideals through observation testing, our inventory has primarily consisted of unpainted girdles. I don''t attempt to dictate a clients personal preferences, I prefer to let them tell me after gaining consumer input. That was the thrust of our observation testing back in 2000-2001. Except at that time it was between what was deemed as "the best reflector image" vs a diamond with "the best BrillianceScope results". At that time I didn''t even know what painting and digging was. Consumer preference was so overwhelmingly in favor of one cut we dropped the painted line and have never looked back.

Peace,