GIA Diamond Cut Grading: Problems with Diamond Dock

[JohnQuixote]

Date: 3/20/2006 1:01:11 PM
Author: strmrdr

Im wondering if the biggest difference in the labs when it comes to painted girdles is the basic method of cut grading they are using.

AGS is actualy running the full data scans and if they meet the brightness and contrast criteria in the computer program they pass even with painted girdles.

GIA in whatever way is either looking at them or from the scans checking a box that says painted and they get downgraded without other considerations.

Doing it that way good pointing and digging wouldnt get downgraded by AGS but the bad kind would.
Doing it that way they would get downgraded at GIA no matter the performance.
That seems to be what is happening and would be a direct result of a proportion based system(gia) vs a performance based system(ags).

The whole post is a good summary.

Edited to add: This fresh from AGS regarding the position that both organizations (AGS/GIA) recommend against painting:

"this generalized statement is misleading. We neither endorse nor oppose ‘painting’ or ‘digging’. We ray trace 3D models of diamonds. If the stone gets the values for brightness, contrast, dispersion and leakage - it gets the grade."

Strm - your wording was eerily similar. Are you wire-tapping the labs?

 

[strmrdr]

LOL no John just starting to put 2 and 2 together.
This mess is starting to make sence to me.

 

[adamasgem]

This is a letter from Peter at AGSL , I will post the two pdfs he sent...

Gentlemen:

In June of last year we disseminated the attached information to the industry. This .pdf file shows how much a cutter can ‘paint’ or ‘dig’ the upper halves and still expect to get AGS 0 light performance for a round brilliant with 50% star length and 80% lower girdle height.

I have been reading the posts on Pricescope about ‘Problems with Diamond Dock’. One of the posts from michaelgem says “Both organizations recommend against painting”. From my perspective, this generalized statement is misleading. We neither endorse nor oppose ‘painting’ or ‘digging’. We ray trace 3D models of diamonds. If the stone gets the values for brightness, contrast, dispersion and leakage - it gets the grade.

The above topic did get me to thinking about ‘painted’ upper halves and we are going to ray trace stones with varying amounts of ‘painting’ with star / lower girdle combinations other than the 50 / 80 to see how much a cutter can ‘paint’ and still get AGS 0 light performance in our system. We’ll make this information available to all.

Also attached is a .pdf file that cross-references lower girdle height versus lower girdle length. This chart was created and released last year by Jason Quick in our lab and Bruce Harding (who posts as Beryl on Pricescope). Essentially, as I understand it, AGS and DiamCalc use lower girdle height. GIA and Sarin use lower girdle length. Neither is right or wrong, they just are. This chart allows everyone to communicate with each other accurately.

Please feel free to post this information to Pricescope.

Heartily,

Peter Yantzer, Director

American Gem Society Laboratories

 

[adamasgem]

This is the indexing study for 50% stars and 80% lower girdle halves

 

[adamasgem]

This is the lower girdle cross reference chart

 

[strmrdr]

Thanks Marty, Thanks Peter

 

[JohnQuixote]

Date: 3/20/2006 2:59:12 PM
Author: strmrdr

LOL no John just starting to put 2 and 2 together.
This mess is starting to make sence to me.

Hehe. Strm’s process of putting 2 and 2 together…

Look at 2.
Cross-check 2 and look again.
Might be 2 but need to prove it.
Separate each component of 2.
Now you have 1 and 1.
Evaluate 1. Is it really 1?
Find lab reports on 1.
Post 1 for feedback.
Research all previous posts on 1.
Do a background check on the integrity of past 1s.
Put 1 in earrings and pendants.
Put grease on the pavilion of 1.
Get a scan of 1. Use IntegerCalc and play with 1.
Consensus is that it is 1.

Ok. 1 seems to be 1… Now let’s go look at the other ‘1.’

(repeat)

 

[strmrdr]

rofl
John thats too close to the truth its scary :}

 

[dhog]

rhino

if the diamond dock could emulate real sunlight
you might be able to photograph real fire and at
the same time get a blue sky even with the stone
tilted in a viewers approx. angle

 

[strmrdr]

Date: 3/20/2006 4:26:18 PM
Author: dhog
rhino


if the diamond dock could emulate real sunlight

you might be able to photograph real fire and at

the same time get a blue sky even with the stone

tilted in a viewers approx. angle

You have to be careful there, you go too far and you get the jewelery store effect with the trick lighting that makes frozen spit look good.
Direct sunlight or bright direct lighting is not the best lighting for separating diamonds.

 

[dhog]

this one also shows head blocking some of the light
these are A CUT ABOVE

 

[dhog]

Date: 3/20/2006 4:33:17 PM
Author: strmrdr

Date: 3/20/2006 4:26:18 PM

Author: dhog

rhino



if the diamond dock could emulate real sunlight


you might be able to photograph real fire and at


the same time get a blue sky even with the stone


tilted in a viewers approx. angle

You have to be careful there, you go too far and you get the jewelery store effect with the trick lighting that makes frozen spit look good.

Direct sunlight or bright direct lighting is not the best lighting for separating diamonds.

and since I live in calif. and its a desert where I
live just like in carlsbad you would think they would
of thought of direct sun or maybe its not important to you.

 

[michaelgem]

I spent today talking to Paul Slegers and Brian Gavin and then Peter Yantzer to get their take on the accuracy of all the information I have posted recently, as well as how they feel it is being perceived.

This below email from Peter and subsequent discussion with him indicate: To say that AGS recommends normal indexes over painting was too strong a generalization of what he previously told me . As you can read, he believes that the point where painting will drop a diamond from AGS0 will vary based on the diamonds other proportion and angle combinations. He is going to explore those limits for a number of proportions and report his findings.

Brian and Paul were extremely informative as well. They both validated the technical points of my posts on clicks, tangs, and painting. There was too much information exchanged to post here, except for one most important detail.

The extent of painting employed in Brian’s New Line is about 4 degrees. Brian says that the look and performance of the New Line diamond is not just about painting, but about the placement and angles of all the brillianteering, both top and bottom. His New Line has no trouble obtaining an AGS0 for cut.

I thought, based upon my early research using Gemcad and DiamCalc, that a greater extent of painting was required to obtain the red-black, no white image that is the hallmark of this diamond type. Based upon Brian’s discussion and pending Peter’s exploration I am putting that belief on hold.

We will all stay tuned as Peter explores the limits of painting in the AGS grading system.

Gentlemen:

In June of last year we disseminated the attached information to the industry. This .pdf file shows how much a cutter can ‘paint’ or ‘dig’ the upper halves and still expect to get AGS 0 light performance for a round brilliant with 50% star length and 80% lower girdle height.

I have been reading the posts on Pricescope about ‘Problems with Diamond Dock’. One of the posts from michaelgem says “Both organizations recommend against painting”. From my perspective, this generalized statement is misleading. We neither endorse nor oppose ‘painting’ or ‘digging’. We ray trace 3D models of diamonds. If the stone gets the values for brightness, contrast, dispersion and leakage - it gets the grade.

The above topic did get me to thinking about ‘painted’ upper halves and we are going to ray trace stones with varying amounts of ‘painting’ with star / lower girdle combinations other than the 50 / 80 to see how much a cutter can ‘paint’ and still get AGS 0 light performance in our system. We’ll make this information available to all.

Heartily,

Peter Yantzer, Director

American Gem Society Laboratories

 

[adamasgem]

Date: 3/20/2006 4:33:17 PM
Author: strmrdr

Date: 3/20/2006 4:26:18 PM
Author: dhog
rhino


if the diamond dock could emulate real sunlight

you might be able to photograph real fire and at

the same time get a blue sky even with the stone

tilted in a viewers approx. angle

You have to be careful there, you go too far and you get the jewelery store effect with the trick lighting that makes frozen spit look good.
Direct sunlight or bright direct lighting is not the best lighting for separating diamonds.

And if you want to get really sophisticated, using an unbiasing 5000+ point envirionment (not 12 LEDS) that simulates natural shady conditions under a tree, like what I was funded by EightStar to develop as a consistent, unbiased envirionment, then you can start to see what is going on with fire versus cut.

Top row actual photos, bottom row stones put on a black background and composite increased in saturation. These were done with the original prototype device i built, and I'll be building a more inexpensive model (the patent is now mine solely, the prototype in others hands right now), as we no longer have to increase the saturation to show the effects of fire. (The stone on the left was rotated slightly for the bottom composite.)

As you rotate any stone about its table to culet axis, each facet might light up an entirely differnt color. The more assymetrical the stone, the smaller the patches of fire, and you get dead areas, like the stone on the right, as opposed to the broadflash fire in optically symmetric stones like that on the left. You also appear to get color mixing with assymetric stones, such that they start to appear muddy and more earth tone, rather than purer spectral hues.

By the way, the source is white light with a high color temperature simulating that of the shade. The stones were all photographed in the SAME envirionment, from the SAME overhead perspective, with the SAME dappled lighting envirionment, containing over 5000+ points of light. To give one a perspective, the grayish background is a pure white, spectrally flat, NIST reflectance standard. Lest anyone complain, I also have shots with a pure black background (NIST standard), but I don't have the time to dig those out, but they show the same qualitative effects of symmetry and precision in cutting.

EDIT: I might note that these are greatly reduced quality images to meet the 100K posting limits

 

[tarssarb]

Date: 3/20/2006 3:09:29 PM
Author: adamasgem
This is the indexing study for 50% stars and 80% lower girdle halves

Well, to me the interesting number is the expected weight. Clearly my stone wasnt painted for the purpose of keeping it above 1 carat which I find extremely nice to know. (ags mid feb 2006).

For a 40.8/34.8 combo with 57 table, the weight gain from normal to max painted listed on that table was a factor of 1.0046. So any stone weighing more than 1.0046 carats wasn''t painted in order to exceed 1 carat. I knew my jeweler was using a good source! Anyway, if it wasn''t done for weight, then it was done intentionally for style as it has the normal symmetry pictures of a good painted stone. I was worried for a while that it was some trick I should have been looking out for. I am now satisified with the minutia you guys are discussing in these threads.

Interestingly, it would have been more worthwhile to make the table a 56 (factor 1.0054) if the rough allowed it than to paint the stone to the ags pdf standard (assuming this is an all encompassing list).

Though as I said before, i have seen an eightstar and believe both the comments of both marty and rhino (broadflash fire versus a somewhat grey contrast) as well as my comments of its representation in bscope.

Rhino: I just wanted to say that i found your comments about black background for closed bezel and grey for open back mountings to be simple and insightful for the average shopper. However, I think the consumer trust issue with the jeweler''s lighting needs much improvement.

(Marty, I will send you email later this week for fun to say hi. This is likely my last pricescope post; my ring is ready to present and is simply stunning!).

 

[strmrdr]

Way kewl Marty
I love diamonds under a tree on a sunny day.
Its my favorite envirement.

 

[JohnQuixote]

Date: 3/20/2006 5:08:54 PM
Author: adamasgem

And if youwant to get really sophisticated, using an unbiasing 5000+ point envirionment (not 12 LEDS) that simulates natural shady conditions under a tree, like what I was funded by EightStar to develop as a consistent, unbiased envirionment, then you can start to see what is going on with fire versus cut.

Top row actual photos, bottom row stones put on a black background and composite increased in saturation. These were done with the original prototype device i built, and I'll be building a more inexpensive model (the patent is now mine solely, the prototype in others hands right now), as we no longer have to increase the saturation to show the effects of fire. (The stone on the left was rotated slightly for the bottom composite.)

As you rotate any stone about its table to culet axis, each facet might light up an entirely differnt color. The more assymetrical the stone, the smaller the patches of fire, and you get dead areas, like the stone on the right, as opposed to the broadflash fire in optically symmetric stones like that on the left. You also appear to get color mixing with assymetric stones, such that they start to appear muddy and more earth tone, rather than purer spectral hues.

By the way, the source is white light with a high color temperature simulating that of the shade. The stones were all photographed in the SAME envirionment, from the SAME overhead perspective, with the SAME dappled lighting envirionment, containing over 5000+ points of light. To give one a perspective, the grayish background is a pure white, spectrally flat, NIST reflectance standard. Lest anyone complain, I also have shots with a pure black background (NIST standard), but I don't have the time to dig those out, but they show the same qualitative effects of symmetry and precision in cutting.

Marty I trust your patents are in order! I think this is the first time these photos have been 'seen' on PS (or any public forum), am I right? Very exciting.

The first time you explained this to me I was in geek Nirvana; someone was explaining, scientifically, what so many people describe in these diamonds aesthetically.

 

[Rhino]

Gettin ready to head out to my sis' b'day party but will try and answer some. Tim will be on vacation this week and I'll be taking the brunt of the incoming so I may not be able to post here during the week as much as I'd like. Please forgive.

Date: 3/20/2006 10:34:26 AM
Author: dhog

the photo to me that you posted looks to be
dark in all corners. I WOULD SUGGEST looking for other
lighting enviroments and or look into the following

So outside in direct daylight in the shade is not good enough?
Outside on cloudy day conditions with pavilions covered as per Pete Yantzers instructions are not good enough?

You are disqualifying 2 of the best lighting environments that depict brightness dhog.

Date: 3/20/2006 10:34:26 AM
Author: dhog

HDR-HC1 owners should be very careful when trying to mount a filter behind the stock lens hood. My UV filter moves the hood forward about .225' causing still images to vignette (darkening at the corners) at widest zoom. Video is fine - no vignetting. However, still images have a wider field of view and have a serious problem.

While you're expertise in figuring out which camera I used is impressive, you got it all wrong however. UV filter yes. Forward hood no.

rhino do you really like using video camcorders to take still shots.

When I am at home and my Canon's are at the job yes. However, as demonstrated it doesn't make a bit of difference what camera I use. The same effects are captured in each of those different environments no matter what camera is used. Shay, an unbiased layman could even see those differences in the photography that our observers see with their eyes. The DiamondDock and consumer response concurs whether viewing under the diamonddock or natural daylight. It makes no difference.

You know what I don't understand (and Garry, please don't take this personally). Garry can post some shots of 2 cubic zirconia (not even diamonds and some out of focus), of which at this point we know nothing about (haven't had a chance to read everything in this thread just yet in case he did post the stats), I offer photography in the best lighting conditions to depict brightness with some of the best equipment available for the job, on top of freely supplying the information on the stones and not once do you question, not one bit, about Garry's photography or the diamond simulants in question.

In the other thread, and this one, I was getting hammered with ... (off the top of my head)

a. there was a .4 degree variance in the pavilion angles of one stone...
b. there might be strain in one stone
c. are the diamonds the same color
d. do both diamonds have equal optical symmetry ....
e. there might be a camera hood causing darkness on one stone and not the other...
f. perhaps the camera is too much in front of one diamond than the other...

I have not seen one question raised concerning the 2 faux stones Garry used to arrive at many of his conclusions.

Am I the only one here who finds this odd?

Garry ... let's see some hard data on the cz stones you used. While I could contend the fact that they are not even diamonds, I give you the benefit of the doubt, however lets see the data please. I am curious.

Sorry I can't stay longer ... gotta head out now. Not sure how soon I can return but as Arnie would say ... I'll be back.

 

[WinkHPD]

Date: 3/20/2006 9:44:21 AM
Author: Serg

Please publish two simple answer

1) What is GIA cut grade for Brain or Paul diamonds?
2) What is AGS cut grade for Brain or Paul diamonds?

It will stop commonalities game.

Serg,

I can not answer for Brian''s stones, but I know that some EightStars would be graded as low as Good on the GIA scale and I believe that Brian would also get Very Good and Good for his painted stones. These stones would get AGS 0 and 1 cut grades from AGS. EightStar has quit getting the reports that give the cut grades, the do not feel it necessary to get a third party to evaluate their diamonds for cutting, but the information is available to them and the diamonds would have AGS 0''s and 1''s if they wanted the full Diamond Quality Document.

Obviously I feel it absurd that a steep deep should be graded as Excellent and an Eightstar as only a good, especially if the stones were supposedly put into these catagories for thier appearance. Of course, every one is entitled to an opinion, and that is mine...

Paul does not paint his stones and gets normally AGS0 and once in a while an AGS1 when he runs into a difficult polish, diamond rough, as you know and understand, does not always let the cutters do what they would like. I believe that Paul''s stones would get GIA excellent but I do not believe that any have been submitted since the start of the new system as Paul switched some time ago to AGS for the quality of their information. He may have submitted one or two for informational purposes, but I do not know this and would have to let him respond to this if he has.

Wink

 

[Garry H (Cut Nut)]

Date: 3/20/2006 6:58:42 PM
Author: Rhino
I have not seen one question raised concerning the 2 faux stones Garry used to arrive at many of his conclusions.

Am I the only one here who finds this odd?

it seems you have not read the article still then Rhino?
The section with the CZ was a small addition - there are about 10 sections and topics - most are based around 3 GIA graded stones. The CZ part was a little after thought, because as you well know I have tested Brilliancescope, ISee2 and Imagem. (BTW none of these instruments downgaded the bad stone anywhere near as they should).
I will email you the article so it is easy for you to print and read at your leisure. (anyone else find their comprehension improves reading from hard copies?)

 

[adamasgem]

Date: 3/20/2006 6:58:42 PM
Author: Rhino



You know what I don''t understand (and Garry, please don''t take this personally). Garry can post some shots of 2 cubic zirconia (not even diamonds and some out of focus), of which at this point we know nothing about (haven''t had a chance to read everything in this thread just yet in case he did post the stats), I offer photography in the best lighting conditions to depict brightness with some of the best equipment available for the job, on top of freely supplying the information on the stones and not once do you question, not one bit, about Garry''s photography or the diamond simulants in question.

In the other thread, and this one, I was getting hammered with ... (off the top of my head)

a. there was a .4 degree variance in the pavilion angles of one stone...
b. there might be strain in one stone
c. are the diamonds the same color
d. do both diamonds have equal optical symmetry ....
e. there might be a camera hood causing darkness on one stone and not the other...
f. perhaps the camera is too much in front of one diamond than the other...

I have not seen one question raised concerning the 2 faux stones Garry used to arrive at many of his conclusions.

Am I the only one here who finds this odd?

Sorry I can''t stay longer ... gotta head out now. Not sure how soon I can return but as Arnie would say ... I''ll be back.

There probably weren''t any questions because people didn''t perceive it as a Shell game.. It was what it was, two SAME stones (CZ''s) under different lighting conditions. Just as in Sergey''s thread. A balanced perspective.

 

[WinkHPD]

Date: 3/20/2006 2:59:12 PM
Author: strmrdr
LOL no John just starting to put 2 and 2 together.
This mess is starting to make sence to me.

Now that''s scary! 99% of the trade will have difficulties with this thread, Wink included, and here is the public beginning to understand better than we do! Good on you Storm!

Wink

 

[WinkHPD]

Marty,

I loved the photos! Thank you for sharing this at last with the public, and I can not wait for you to make me one of these new toys in an affordable version. I thiink it was at least two years, or was it three, when you first told me about this and I am so happy to see it coming to fruition.

Wink

 

[WinkHPD]

RE: The above topic did get me to thinking about ‘painted’ upper halves and we are going to ray trace stones with varying amounts of ‘painting’ with star / lower girdle combinations other than the 50 / 80 to see how much a cutter can ‘paint’ and still get AGS 0 light performance in our system. We’ll make this information available to all.

This was the most exciting thing from my conversation with Peter this morning. This is what I love about AGS and would love to start loving about GIA. Peter and AGS are completely transparent. They will monitor a site and especially a thread like this then set out to do new research on the questions raised and then immediately announce what they are doing and share the results with us as quickly as possible, then look for new input. WOW!

GIA will be teaching a cut grading class at the AGS facility in Vegas soon, and AGS intends to send at least one member of their staff to learn the GIA system better. I think it important to note that while they may dissagree on the details of their respective grading systems that they both continue to work closely together and learn one from the other. This to me is a very good sign.

Wink

 

[strmrdr]

Date: 3/20/2006 7:25:13 PM
Author: Wink

Date: 3/20/2006 2:59:12 PM

Author: strmrdr

LOL no John just starting to put 2 and 2 together.

This mess is starting to make sence to me.

Now that''s scary! 99% of the trade will have difficulties with this thread, Wink included, and here is the public beginning to understand better than we do! Good on you Storm!


Wink

Think simple.
When I tried to come up with a complicated answer to the problem it made no sense.
Went simple and its falling into place.
Remember GIA said the goal was that it could be applied using the lowest quality tools and by appraisers in the field where AGS you need the high end scanners and today''s scanners are barely acceptable, helium is too slow and sarin is less precise and ogi well I don''t want to get sued :}

A lot of the answers are staring us in the face:
Why did GIA allow steep deeps.. industry observers liked them, Them asking Jon have you looked at them lately backs that up.

Why did GIA ban painted girdles.. I think it may come down to the low end scanners cant handle them.

 

[strmrdr]

Take this one step further:
cost to implement for an appraiser:

GIA: computer $500, internet connection $10 a month, scanner $5000

AGS: Computer $500, internet connection $10 a month, scanner $15000+, AGS membership to access the software $?, Tied back to AGS and a value add for the reports that comes at a premium.

AGS: real simple unofficial results: handheld ASET, and likely eventually a handheld DScope - dispersion scope. But if you want the real score its big $$. But the reason they release them and cheap is that anyone in the chain can tell if they would make more money by sending the diamond to AGS.
It also creates buzz in the industry and makes the dealers feel involved. Its great PR.
Just look at my ASET thread for asschers.
They haven't released the cut grades for it yet but because they allowed DC to implement ASET there is buzz already and people are looking forward to it.
I feel so used :} lol

 

[WinkHPD]

Date: 3/20/2006 8:41:17 PM
Author: strmrdr
Take this one step further:

cost to implement for an appraiser:

AGS: Computer $500, internet connection $10 a month, scanner $15000+, AGS membership to access the software $?, Tied back to AGS and a value add for the reports that comes at a premium.

I believe this statement to be in error. One, I am not sure why the Sarin for GIA would cost less than for AGS, but most importantly I do not believe that AGS membership is necessary to access the software. I am not positive on this, but I believe that AGS will allow anyone who wishes to do so to purchase the software. Perhaps we can get an update from Peter on this.

Wink

 

[strmrdr]

Date: 3/20/2006 8:52:37 PM
Author: Wink

Date: 3/20/2006 8:41:17 PM

Author: strmrdr

Take this one step further:


cost to implement for an appraiser:


AGS: Computer $500, internet connection $10 a month, scanner $15000+, AGS membership to access the software $?, Tied back to AGS and a value add for the reports that comes at a premium.

I believe this statement to be in error. One, I am not sure why the Sarin for GIA would cost less than for AGS, but most importantly I do not believe that AGS membership is necessary to access the software. I am not positive on this, but I believe that AGS will allow anyone who wishes to do so to purchase the software. Perhaps we can get an update from Peter on this.


Wink

the low end sarin isnt precise enough for the work they do with the data they would be wacko to allow the low end sarin/ogi data to be used.
It may have changed but last I heard the software was only going to be available to AGS members.

 

[dhog]

Date: 3/20/2006 4:33:17 PM
Author: strmrdr

You have to be careful there, you go too far and you get the jewelery store effect with the trick lighting that makes frozen spit look good.

Direct sunlight or bright direct lighting is not the best lighting for separating diamonds.

since you know so much about lighting
lets go fishing.

on page 7 of this thread I posted a photo of
my wifes rings and asked for answers. You might
want to go look at the photo.

lets assume that the lower part of the photo is the location of your head when viewing the diamond dock.

next lets assume that the sunny part at the top
of the photo is the light at the top of the diamond
dock.

since fish are attracted to lures in the same
color as the inside of the diamond dock and by
the way this lure just happens to be the same
color as the background on P/S.

I need you to cast the lure out of the photo
and tell me where it landed. pretty cool

happy fishing

 

[strmrdr]

Date: 3/20/2006 9:30:45 PM
Author: dhog

Date: 3/20/2006 4:33:17 PM

Author: strmrdr


You have to be careful there, you go too far and you get the jewelery store effect with the trick lighting that makes frozen spit look good.


Direct sunlight or bright direct lighting is not the best lighting for separating diamonds.

since you know so much about lighting

lets go fishing.


on page 7 of this thread I posted a photo of

my wifes rings and asked for answers. You might

want to go look at the photo.


lets assume that the lower part of the photo is the location of your head when viewing the diamond dock.


next lets assume that the sunny part at the top

of the photo is the light at the top of the diamond

dock.


since fish are attracted to lures in the same

color as the inside of the diamond dock and by

the way this lure just happens to be the same

color as the background on P/S.


I need you to cast the lure out of the photo

and tell me where it landed. pretty cool


happy fishing

Id rather go shooting :}