GIA Diamond Cut Grading: Problems with Diamond Dock

[adamasgem]

A few of us in the trade may seem to be little "hard" on GIA (a/k/a "trashing") and what they do or produce, but if one looks at the history of changing "standards", coverups, differences in what they do and what they say(teach), "hidden" faults in diamonds like "non callable extra facets", convenient redefintion of words like "none", and in the latest GIA Certifigate scandals, you might wonder if their is a causal relationship behind "stands" that are taken at GIA and things (management decisions) that led to the "Certifigate" coverup. It is all about $$$$

The latest online "memo" http://idexonline.com/NewsLetter.asp?id=176 calling for the ouster of the man at the helm of this once prestigous institution, makes it abundantly clear that I am not entirely alone in my thinking. Unfortunately that may not happen unless more internal heads start to roll based on supposed FBI investigations.

If one also goes to their news archives and looks up "certifigate" there are many more editorials about the coverups on the Idex website..

It is a shame that most of the hard working people at GIA have to put up with their management. I know many who have left because they couldn''t or wouldn''t put up with the internal BS I have been led to believe after countless hours of talks with many.


‘The only thing necessary for the triumph [of evil] is for good men to do nothing.’ Edmund Burke

 

[Modified Brilliant]

‘The only thing necessary for the triumph [of evil] is for good men to do nothing.’ Edmund Burke

...a great quote indeed





www.metrojewelryappraisers.com

 

[Garry H (Cut Nut)]

This thread is a month old:
It began as a discussion on Diamond Dock and GIA''s grading system.

My Journal article http://journal.pricescope.com/Articles/37/1/GIA-Excellent-Cut-Grade-Case-Study.aspx was a fundemental part of it which was based on some testing that I did with DD.

It developed into a discussion about painting etc after Rhino introduced some different stones. the first 2 pages of threads are about the topic - before it wandered away.

At the time Rhino had not read my article - but has since and I beleive he is preparing a rebutal.
I welcome that as healthy debate as that is how we all make perceptual advances

Date: 3/15/2006 4:41:57 PM
Author: Rhino
I appreciate a healthy dose of skepticism and I am a firm believer in putting any technology through rigorous testing, primarily how it corellates to human observation. I am all for that.

My question is simple.

What if you take a pair of comparison stones and observe them for brightness in

a. Standard daylight environments such as outside on a cloudy day.
b. Outside in sunlight but in the shade.
c. Standard overhead office lighting (overhead fluorescents)
d. Diffuse LED''s (as opposed to direct)
e. Then lastly the GIA DiamondDock

and you see the same exact optical phenomena in each and every instance?

Rhino we never saw this material - it would address the concerns that I had. I believe your video was made without the microphone turned on - but I am sure you could air some contnet with a voice over?

Or do it again?

However from my few days with Diamond Dock I doubt you see the same exact optical phenomena in each and every instance?

I also imagine by now that many consumers must have walked into stores and seen diamonds displayed in DD? If so - please tell us your experiances and if you bought diamonds based on that tool etc?

 

[Garry H (Cut Nut)]

bump

 

[Rhino]

LOL... was just about to sign off and caught this. Wifey is waiting to watch a flick with me.

I have completed most of the rebuttal in written form and will be editing the video portions this Wednesday and Thursday. I"ll be finished with the written portion sooner than the video. Shall I post the written portion first? I thought all of it together would be better but if you''d prefer to read the written portion first (with some photography I''ve taken and some interesting things in your own photography) I''ll be happy to post that once completed beforehand if you like. I love a friendly debate and am always open to ideas as long as it doesn''t get personal.

Peace,

 

[Garry H (Cut Nut)]

Post away Jonathon - lets get going

RockDock and i had slanging matches years ago - but i learned it achieves nothing.
I will go the ball mate - not the man

. But I go hard, so no whimping if i beat the bejeezuus out of you

 

[Garry H (Cut Nut)]

This is a slide I made for the thread Simple Science: Shallow or deep.

You should play with this tool here folks http://www.cutstudy.com/cut/english/comp/scint1.htm

All the stones have 57% tables and 34.5 crown angles. the shallow pavilion on the left has a central zone of about 10 degree radius where the first sparkles would come back to a viewers eye (the left to the left eye and the right side to the right eye).

I placed 2 faint lines in the upper area - these are my guess at the center point of each of the 2 Fluoro tubes in the GIA Diamond Dock. Where ever there is a flash where the tubes would be - there will be a bright sparkle somewhere in the diamond.

See why GIA would not favor shallow stones. But what if we tilted the DD over towards us? I bet if you try this Jonathon - I bet you will see how it would be possible to design a DD that led to a preference for shallow stones.

 

[strmrdr]

A light box for grading cut should not favor any particular cut so designing one for shallow stones would be a step in the wrong direction.

What matters is designing a box that duplicates the real world as much as possible.
With the tubes only the DD does a decent job of this.
Now is it a good lighting condition to tell one diamond from another?
I can tell the difference in personality in different cuts in photos under the DD. So dunno beyond that.....

The LED's with the tubes I could also accept as semi-realistic.

The LED only lighting is one lighting condition I have a problem with and my question is how much of the observation testing was done LED only.
As a demo tool to say this is fire I can sorta see the point of using LED's only but not as a cut grading tool.
But real world ... pending more info my opinion is no the LED only is not good.
Im keeping an open mind on it and maybe ill see something soon that convinces me otherwise but until I see non-led lighting that looks like the led lighting it will remain a fake environment to me.
My 2 cents

 

[adamasgem]

OK I''ll be nice.. But if someone is blowing smoke, I''ll set up a wind tunnel...

GIA''s attempted study using hemispheres, both theoretical and physical, at least was symmetric and non aliasing.. allbeit that the quazi uniform illumination was not realistic in the least

A limited pin point hot spot environment,like DiamondDock, is aliasing..

I think I know what to do, but given the prevalence of intellectual property theft in this industry and tendency for certain organizations to controll everything they can get their hands on, will not comment until I play the same game by filing a patent application myself.

BTW Garry, while the chromatic flare type of diagrams are a limited usefulness analysis tool (based on the same GemPrint non laser type of beam illumination), they DO NOT reflect the overall abiliity of a stone to generate fire, contrary to GIA''s published methodology.

 

[Garry H (Cut Nut)]

Marty i am not using the http://www.cutstudy.com/cut/english/comp/scint1.htm tool to display or consider fire - it is purely to assess the direction from whence lights could be placed and be visible as flashes in the diamond being examined.

I think the image above shows that shallow stones would not normally be viewed in a direction in DD that would enable them to be in a position to recieve much light.

Storm you are happy to have light coming from a very specific direction - which in itself is a variable given bench height, chair height, observer height and not to mention the variability of background lighting in the various rooms and stores where DD might be situated?


Storm you still happy that the tubes in the DD are very close to the diamond?
You have not attempted to do any tests like Sergey and Yuri''s that show that very strong lamps very close to a diamond do not create a "real world" environment?

They make the contrast between dark and light very stark.

 

[strmrdr]

Date: 4/24/2006 7:09:42 PM
Author: Garry H (Cut Nut)

Storm you are happy to have light coming from a very specific direction - which in itself is a variable given bench height, chair height, observer height and not to mention the variability of background lighting in the various rooms and stores where DD might be situated?

I compared a diamond in person to DD photos of that diamond.
With just the tubes its close enough for me to consider it realistic.
Much more so than the vendor photos we see on a lot of websites.
You would have the same variables in a light room.
The only way to eliminate them would be a sealed box.



Storm you still happy that the tubes in the DD are very close to the diamond?

farther away would be better but it works well enough im not saying its perfect but it is not that bad either

You have not attempted to do any tests like Sergey and Yuri''s that show that very strong lamps very close to a diamond do not create a ''real world'' environment?

yes with the same diamond, the DD does not have that effect to a great extent, the lights have to be much brighter and or closer


They make the contrast between dark and light very stark.

the DD makes diamonds look slightly more gray than in person
Is it the lighting or the gray walls? .. who knows .. but its closer than a lot of other images iv seen to the real world.

 

[strmrdr]

have ya considered?

If i was a better artist and not dead tired the angles of the blue lines would be closer to the same but ya get the idea....

 

[Garry H (Cut Nut)]

Thanks Storm.

1. The light source is NOT ever going to ever be anything like the same intensity because intensity falls away as a log function. Double the distance = 4 times the intensity needed to get the same result. The light in DD is just way too close to the diamond. the only way you would get close to that intensity from a ceiling mounted light would be with an intensly search light like those used for spotting planes and hunting animals at night.

2. Because of that relative intensity the non illuminated areas become effectively black or very very dark. Even if there is a ceiling light over your shoulder - it will provide little to no bright sparkles that can be seen with a human eye that has adapted to the DD background and brightness from the diamonds being viewed.

 

[Garry H (Cut Nut)]

3. and this third point shows (using AGS data for the 3 stones in my survey thanks to Peter Yantzer) how the normal seating position would lead to a preference for Tolkowsky and deeper stones, and alsias away from shallower stones.

But if the viewer stood up and looked directly down - as I would like Jonathon to try with some shallow stones - we would expect to see the opposite aliasing.

 

[strmrdr]

#3 is only valid if the stones aren''t moved or the angles not changed.
From the limited info available it seems the observers were free to move the diamonds.
The overhead light condition is a common condition as is some angle.

Theory is kewl but only when it lines up with the real world and at this point the images under the DD with tubes only lines up pretty well with the real world on the exact same diamond.

What we should do and Jon likely cant without violating the rules but PS could is get a box of 25 signity star CZ''s, create vids of a sample of them under the DD then send them out to volunteers for evaluation and data reporting. That could be done for under $200 if Jon is willing to shoot them for free.
Even better would Leonid and Irina going down and doing the taping.
That way there could be no questions by anyone even the people that hate the D.D. about the results.

 

[adamasgem]

Date: 4/25/2006 5:23:03 AM
Author: Garry H (Cut Nut)
Thanks Storm.

1. The light source is NOT ever going to ever be anything like the same intensity because intensity falls away as a log function. Double the distance = 4 times the intensity needed to get the same result.

Hi Garry.. Would you mind explaining "log" function for intensity falloff. I''m in Florida and don''t have my texts readily available so I''m a little confused. I always thought that a point source intensity per unit area fell off as 1/(R^2), but I guess you can make anything a log function, just haven''t seen it presented that way..

BTW Rockdoc, Neil Beatty and I picked up Sergey yesterday at the airport. Me thinks his eyelids were propped up with toothpicks. Looked like a real tired puppy after 20 hours from Moscow..

Interesting discussions...

 

[pricescope]

1/R² sounds right

.

 

[Garry H (Cut Nut)]

Date: 4/25/2006 8:24:29 AM
Author: strmrdr
#3 is only valid if the stones aren''t moved or the angles not changed.
From the limited info available it seems the observers were free to move the diamonds.
The overhead light condition is a common condition as is some angle.
As we so often say - the face up counts by far the most.

Theory is kewl but only when it lines up with the real world and at this point the images under the DD with tubes only lines up pretty well with the real world on the exact same diamond.

What we should do and Jon likely cant without violating the rules but PS could is get a box of 25 signity star CZ''s, create vids of a sample of them under the DD then send them out to volunteers for evaluation and data reporting. That could be done for under $200 if Jon is willing to shoot them for free.
Even better would Leonid and Irina going down and doing the taping.
That way there could be no questions by anyone even the people that hate the D.D. about the results.

What will the CZ survey do?
As Sergey has often said - studying good stones is no way to develop a grading system - it is the most common mistake.

And what about points 1 and 2 and the adjustments to your sketch Storm?