GIA Ex: The Consumers Perspective and the Technologies

[Rhino]

Date: 3/11/2006 3:31:50 PM
Author: Wren
Now Now, stop whacking the poor man. Some of you are basically accusing him of rigging the test!
Personally I want to know the results of the survey.
Let''s face it, all (the majority of) consumers really care about is if the diamond looks pretty or not.

In case you missesd it Wren I already posted the results which are at the bottom of the 1st page. I don''t feel any whacking (at least not yet). It''s ok ... I have my Bat-armor on.

Kind regards,

 

[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?

 

[adamasgem]

Date: 3/12/2006 5:22:23 PM
Author: michaelgem

These simple mirror reflections often result in undesirable glare, especially from the table. This glare reduces the sharp, high-contrast appearance of a diamond. The author’s opinion is that such reflections need not be considered in diamond design, as they have little to do with the attributes of diamond beauty --- brilliance, fire and scintillation.” Michael Cowing

The simple mirror reflections depend on the angle of incidence and are at a minimum of 17% for diamond.

If one assumes equally probable angles of incidence on a facet, they average over 26% of the incident energy..

They DETRACT from recognizing a diamond''s beauty.
I would say they SHOULD NOT BE CONSIDERED in evaluating a diamonds design attributes.

 

[Rhino]

You know what I love about you Marty ... you''re like me in many regards. A natural born skeptic.

Date: 3/11/2006 3:34:41 PM
Author: adamasgem

Out of 25 observers in total so far, 23 picked the GIA Ex in l.e.d. lighting and 23 picked the GIA Ex in daylighting, I kid you not!

I was thrown for a loop with this research!

No surprise there, you can design an envirionment to mask differences, that is all..

Do you feel this phenomena is *only* observable under a GIA DiamondDock? If you recall earlier in this thread I stated rather clearly that if the DD did not emulate natural lighting I would have returned it. While I do not have a photograph on my harddrive of the 2 comparison stones in this study, here is one I took of 2 diamonds, same size, virtually identical angles and table, only difference ... one painted and one not. Attached is that photo taken in natural daylight. No "custome designed" or "rigged" environment to flatter one and not the other. I was sitting on my porch in natural daylight. The same phenomena is observable no matter what daylight conditions you commpare the diamonds in, I would note with the exception of an environment that is primarily reflective light as opposed to brighter direct light. Didn''t I also state rather clearly that I first showed observers in natural daylight coming in from our window and when the reported results were identical each and every time, only then did I stick to the DiamondDock? Come on now Marty.

All the best,
Jon

 

[adamasgem]

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.

I would think that it would effect their metric one way or another as they ray trace all stones, and GIA just outright dismisses them. For GIA to give an EightStar (or New Line), for example, only a Very Good or Good Cut grade, is outright STUPIDITY on their part, among other things..

- 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.

The key word here is "Commercial"


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?

Oh no, I''ve addressed the issue regarding the use of only a faceup view or a faceup view and a single tilt angle for overall evaluation as a criticism of both AGS(15 degrees) and MSU(30 degrees), and I believe both may be looking at the effects and addressing the issue. Both AGS and MSU readily accept critiques, from what I have seen, unlike others..

 

[Rhino]

Date: 3/11/2006 3:34:41 PM
Author: adamasgem

I emailed Al Gilbertson himself to find out the context of his quote. Al was speaking about, what was called at that time “radial symmetry”, a term coined by Kelsey McLeod who worked with Al during the days of DPL. That is the term which was later coined “optical symmetry” by Al and 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. This subject happens to be a peeve of my own and would have liked to see a grade for this as well but to stand back and point the finger at GIA alone for not doing it is moot if you’re not going to level the same accusations at AGS as well.

WRONG As far as I know, AGS raytraces each stone based on the actual scan so that symmetry becomes part of the contributor to the performance grade, while GIA first averages, then ROUNDS, then uses a look up table, ENTIRELY different things.
Ask the question, why does GIA allow an EX cut grade when the symmetry is only the unquantifiable VG. All in the trade always wanted GIA EX/EX (polish/symmetry) in the past, to consider it a top stone, why the change????? You explain it.

I take this as a two part question.

WRONG As far as I know, AGS raytraces each stone based on the actual scan so that symmetry becomes part of the contributor to the performance grade, while GIA first averages, then ROUNDS, then uses a look up table, ENTIRELY different things.

First ... both GIA and AGS do not consider "optical symmetry" in their final grade. This addresses the point I was making and is in context with the direct quote from Al Gilbertson. How do I know this? Becuase not too long ago we received this *new* AGS Ideal and here is it''s reflector images, based off the scan. Optical symmetry is what we would grade as "common". I think you would agree. At the same token Marty, I personally would have liked to see an optical symmetry grade instituted by both labs. You and I are in agreement insofar as the "optical symmetry" or "craftsmanship" issue.

Ask the question, why does GIA allow an EX cut grade when the symmetry is only the unquantifiable VG. All in the trade always wanted GIA EX/EX (polish/symmetry) in the past, to consider it a top stone, why the change????? You explain it.

Very simple actually. GIA acknowledges the fact that there is no "face-up" difference between a VG and an EX grade in these arenas. I think it is something to be applauded and not criticized. Why? Because its true!

Remember, the EX grade is determined by factors that affect face up appearance.

Peace,
Jon

 

[Rhino]

Date: 3/11/2006 3:43:34 PM
Author: strmrdr

Date: 3/11/2006 3:14:33 PM
Author: kenny
That''s it.

I give up.

I''m shopping at the mall from now on.

There is a ton of research that needs to be done yet.
I think this study is a good first step but not the final destination.

The background and lighting questions are good ones that need to be answered.
Repeating the test with the same stones mounted in settings in the DD and on the finger would be a good next step.
Others doing the same with other combos would be a very good idea also.
Anyone that has been paying attention knows that there is a lot of disagreement on what a top diamond is and has been for a long time.
Im of the opinion that there may not be just one right answer.
10-20 years from now the answers may be more clear but the study is just beginning.

Amen to that. One point of note strm. After posting this thread I was notified by AGS labs to make sure that the diamonds used in the comparison were not "backlit" as their algorithms do not account for that. I ensured them that in the first initial 6 exams the diamonds were not backlit in 5 of those 6 and they weren''t. If we mount the diamonds in rings and allow backlighting however I don''t feel it would change results that much as the picture I just posted was of 2 diamonds set in rings (one was my ring the other was a faux ring).

Peace,

 

[adamasgem]

Date: 3/12/2006 6:41:02 PM
Author: Rhino
You know what I love about you Marty ... you''re like me in many regards. A natural born skeptic.

Do you feel this phenomena is *only* observable under a GIA DiamondDock? If you recall earlier in this thread I stated rather clearly that if the DD did not emulate natural lighting I would have returned it. While I do not have a photograph on my harddrive of the 2 comparison stones in this study, here is one I took of 2 diamonds, same size, virtually identical angles and table, only difference ... one painted and one not. Attached is that photo taken in natural daylight. No ''custome designed'' or ''rigged'' environment to flatter one and not the other. I was sitting on my porch in natural daylight. The same phenomena is observable no matter what daylight conditions you commpare the diamonds in, I would note with the exception of an environment that is primarily reflective light as opposed to brighter direct light. Didn''t I also state rather clearly that I first showed observers in natural daylight coming in from our window and when the reported results were identical each and every time, only then did I stick to the DiamondDock? Come on now Marty.

All the best,
Jon

Come on now Jon
What about a dimmer lighting environment where glare isn''t overwhelming fire, like in your picture.
You know, like what you probably used to do, when you were selling EightStars?
Present both sides of the story...

 

[adamasgem]

Date: 3/12/2006 6:54:04 PM
Author: Rhino

Ask the question, why does GIA allow an EX cut grade when the symmetry is only the unquantifiable VG. All in the trade always wanted GIA EX/EX (polish/symmetry) in the past, to consider it a top stone, why the change????? You explain it.

Very simple actually. GIA acknowledges the fact that there is no ''face-up'' difference between a VG and an EX grade in these arenas.

I guess people only look at diamonds in the face up position then, and that should be the only criteria.


I think it is something to be applauded and not criticized. Rather a Bronx cheer for them Why? Because its true!

I disagree, but then again I don''t always take the retailers perspectiver Remember, the EX grade is determined by factors that affect face up appearance. As I said before, I guess people only look at diamonds in the faceup position

 

[Rhino]

Marty ... you''re a kick in the pants.

I hope you''ll be in Vegas this year.

Date: 3/11/2006 3:51:13 PM
Author: adamasgem

Date: 3/11/2006 3:31:50 PM
Author: Wren
Now Now, stop whacking the poor man. Some of you are basically accusing him of rigging the test!
Personally I want to know the results of the survey.
Let''s face it, all (the majority of) consumers really care about is if the diamond looks pretty or not.

NO NO NO.. The ''test'' is HIGHLY influenced by the environment used...

Ans YES the test was sort of ''rigged'' vis-a-vie standard versus painted girdles because Rhino, to my knowledge can''t get them anywhere anymore.

I sure can bossman. While I did cease to get them from one supplier (yet keep a couple on hand strictly for these kind of research purposes), there is another manufacturer of painted girdle diamonds with which I can get as many as I want. After our observation testing in 2000-2001 however they have always comprised a minority count in our inventory (basically reflecting those same research results). Marty ... do you realize you''re inducing a false dichotomy to the readerse by suggesting I somehow "rigged" the observation? You are suggesting to the readers that I am here to paint a dishonest picture. Please do not do this becuase you know my character better than this. There was no rigging. I am not involved in some kind of conspiracy to make anything one way or the other. I didn''t have the observers put special glasses on to make them see one way or the other. They saw it (as well as I and my staff) no matter what daylighting. LMAO ... you''re cracking me up!

Date: 3/11/2006 3:51:13 PM
Author: adamasgem

So next I imagine Rhino is going to take down everything from his web site he used to use to try to sell diamonds with objective information (right or wrong that is was) in the past, retract all he said in the past on PriceScope and other web sites about why this stone or that stone he was selling was the greatest thing since sliced bread, return all his ''tools'', buy a 1000 DiamondDocks and ship one with every diamond, just because there is finally an envirionment that makes any old stone look the same. That''s what I read into this thread. But then I tend to be a cynic anyway when it comes to retailers in general.

By the way, I happen to like Rhino personally...

Haha! I like you too Marty.

I have nothing to retract or return my friend. It is diamonds like this that help me learn, grow and understand more. Garry once said to me ... you will learn more about diamonds as you view those that you''re not accustomed to seeing all the time. I couldn''t agree more. BTW, my position has not changed in 5 of the 6 years I''ve been selling super ideal cuts. I have stated rather publicly what my personal preferences were in many threads. I was mistaken perhaps in one instance. I thought the primary factors contributing to the difference in appearance were due to lower half and star length, and while this certainly does impact certain features (particularly regarding scintillation and pin flash), I didn''t realize the difference of the painted girdles as much as I do now. I have the researchers at GIA to thank for helping me to understand this better. If I didn''t state this earlier, let me say that research gemologist in both GIA and AGS labs have shown me nothing but the utmost respect and cooperation in being able to learn and understand the sciences and intricacies of each of their cut grading systems to better communicate them to the public and help them understand. Upon launch of our new site we have a entirely new cut tutorial reflecting all these changes and the factors that go into them.

Peace,
Jonathan

 

[valeria101]

Date: 3/12/2006 6:49:12 PM
Author: adamasgem

Date: 3/12/2006 6:28:40 PM
Author: valeria101



- 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.

I would think that it would effect their metric one way or another as they ray trace all stones

That''s what I was wondering - how & how much.

I don''t know what AGS''s ray tracing does. The DiamCalc that I do have still assigns a guess-grade of AGS0 to something quite a bit flattened, while the light return metrics take no hit. Contrast does, understandably: at worst it goes ''good-very good'' for such a borderline ''too painted'' AGS0 model.

Attached is the culprit. To me, the ring in Jonathan''s hand (the one to the left) looks this way. And the skinny lower girdle facets just exaggerate the looks. The same folk that like the busy-buddy looks of 1 carat diamonds with 100 facets are not likely to prefer the ''large flash'' look of very painted, IMO.

That GIA exaggerated by weeding out every little bit of sophisticated brilianteering (8*''s, ACA and what not) - no question. I am wondering about the opposite extreme.


Anyway... perhaps I shouldn''t play too much with these

The thread sounds way too serios.

 

[Rhino]

Hi Mike,

I appreciate your input more than you know. As a fellow research gemologist, when you speak my ears are always opened a little wider.

When talking with the GIA cut team I had learned that they also experimented with flesh/skin colored trays as well and had the same results. My primary concern of course was that the visual results weren''t different from natural daylight conditions.

Your article on contrast brilliance was especially helpful during my research of the subject too as that is a major factor determining appearance in both grading systems.

All the best,
Jon

 

[Rhino]

Hi tarssarb,

It''s a pleasure to make your acquaintance. Let me try and address your questions/points.

Date: 3/11/2006 7:35:45 PM
Author: tarssarb
Hi,

Rhino, I love your posts and zeal! However, while this was interesting, it was seriously flawed and I am too fresh to miss the mistake.

You compared GIA EX to painted girdle (similar to eightstar). While interesting, it doesn''t address the orginal experimental objective and you already knew the answer.

I think you misunderstand the objective tarssarb becuase I did not know the answer. If you browse our inventory you will not find a diamiond with leakage under the table such as used in the example. In 6 of the 8 years we''ve been on the net you generally will have never seen a diamond in our stock that has "the ring of death" under the table. Many regulars on the forum who go back with me that far will testify to what I am telling you.

Let me explain why I sought out the following 2 stones for this study.

The GIA Ex is a diamond that does not qualify as an AGS Ideal and the AGS Ideal is a diamond that does not qualify as a GIA Ex.

This is the comparison I wanted to conduct and get consumer input on. Why? Because in my own mind it would either confirm or deny the veracity and science of GIA''s Cut Grading system.

Before this study, and you can ask any forum member this as well, I had a natural bias against steep/deeps. You are talking to the one who coined the term "the ring of death". A term which carries with it some seriously negative connotations. I would still point out that there are many steep/deeps on the market that are dogs. I am learning however (as I have in the past as well), there are always exceptions to the rule and never to place too much stock in any one technology. GIA has discovered these exceptions I believe through observation testing. What made this study most intriguing however is that virtually every technology disagreed with the human observation testing. We have always performed observation testing on our diamonds (making sure they exhibit top optical properties) but this is the first time we''ve ever encountered one that went against so many.

If I had used the comparison you suggest I would have been comparing 2 GIA Ex''s whereas only one would be AGS Ideal. That is not the comparison I was looking to draw. I wanted one that didn''t make it in one system vs another that didn''t make it in the other.

Do you understand why that was the comparison I wanted to draw? If not let me know and I can perhaps expound further.

The correct experiment would be comparing the steep/deep to a AGS/GIA overlap diamond (the generally agreed ideal). If the selection of laymen was 50/50 (ie experimental noise) then the GIA ideal region was properly sized. If 60-86.5% could tell the difference, then it was 1-2 sigma so to speak and made too large

Since I have access to many various kinds of makes tarsarb, I am open to taking these requests and posting the results. Matter of fact I have such stones on hand. That could be the next experiment perhaps. I''d be curious to know the results of that as well!

Date: 3/11/2006 7:35:45 PM
Author: tarssarb

I have now seen a branded eightstar... it does appear to have a body of greyish hue style contrast, but virtually all the light I saw was colored light. I suspect if you redid the test you did in a dark room with one candle, you would get a different outcome. Perhaps people who buy 8star do so for this effect? I did notice a general brightness and white scintillation hit compared to a AGS0 H&A. I should point out it was a very slight nuance to me.

Then you saw exactly what our observers saw. Let me reiterate. The comparison was not that of a pretty diamond next to an ugly diamond. Many observers said what you did. To some the difference was slight, to some a little more obvious. As human beings, we all see things slightly differently and I would never critcize the person whose preference lies with such a stone. In the years I''ve been participating on these forums you will not find one slight word from me regarding stones with painted girdles and neither should anyone now. I am simply reporting what consumers and staff have observed who I showed the comparison to.

Lesson: Technologies do not detect painting (BrillianceScope and Isee2). It is however a feature that can be detected in reflector technology and ASET probably explains it best. I''ll expound on this later.

Kind regards and thanks for your questions.

 

[Rhino]

Date: 3/11/2006 8:46:39 PM
Author: adamasgem

Date: 3/11/2006 6:45:41 PM
Author: michaelgem

GIA believes and I reluctantly agree that use of a neutral brightness background is a key element in obtaining comparison tests that correlate well with human judgment of diamond beauty in typical mounting and viewing circumstances.

Michael Cowing

www.acagemlab.com

I guess that we should silver back (foil back) all diamonds then..

Like I said before, make an envirionment that makes the point you want to push.. screw the real aspects of what makes a diamond zing..

This thread is not about any science, it is about marketing... and maybe kissig butt..

https://www.pricescope.com/community/threads/guess-who-is-new-gia-alumni-vice-pres-for-long-island-chapter.24699/

GIA does not own me Marty. I resent you saying and suggesting that my opinion can be bought or that I am trying to kiss butt. Ask our common friend Todd, who btw happens to agree with the majority of the observers as well. I had hoped you would not resort to this kind of slander on my character. I will not go there.

I guess I''m trying to kiss AGS''s butt too because I am seeking membership in their organization?

 

[Rhino]

Date: 3/11/2006 9:51:41 PM
Author: kenny
Ouch!

Brian''s ''GIA EX, Let the buyer beware'' thread opened my eyes to GIA''s new suspiciously huge ''Excellent'' cut bucket.

Rhino since you are Alumni Vice President for the GIA''s Long Island Chapter I''m afraid that this thread does take on the appearance of damage control.

I think reminding us of this affiliation at the beginning of this pro-GIA thread would have been appropritate since the thread of yours thread that Marty linked us to is over a year old.

Kenny ... if you recall last year AGS was being railed by another forum and pointing to a technology to disprove the science behind thier cut grading system. I was able to demonstrate the fallacy of thier arguement by garnering consumer opinion on the said type of stone they were criticizing. I am not doing anything differently now.

If the consumers in our survey had chosen differently (and I had a bias against steep/deeps before this survey which is plainly documented over 6 years I''ve been participating on these forums) do you think I would come here and lie about the results just to kiss GIA''s butt? I''d drop the GIA role in a hearbeat if it meant not being truthful and honest to my conscience and integrity.

 

[Rhino]

Date: 3/11/2006 11:29:08 PM
Author: dhog
I GUESS NO MORE PHOTOS SORRY FOLKS

Hi d,

I do not attempt to appraise diamonds by photographs not taken or inspected by myself.

The reason led''s are used to observe fire is becuase they are a stronger more direct light source. In jewelry stores, insurance companies will not cover the jeweler if he takes merchandise out of their store, therefore we are prevented from bringing diamonds outside. Showing diamonds under l.e.d. lighting produces a similar effect however a general rule of thumbs when observing diaimonds ... the stronger the light source the more intense the reflections will be.

Regards,

 

[Rhino]

Date: 3/11/2006 10:10:07 PM
Author: Midnight
New GIA Ex(includes steep/deep) = ''Old'' AGS0(also included steep/deep)

''New'' AGS0 = Excluded steep/deep

It seems like GIA is saying that consumers can''t tell the difference between steep/deep with GIA EX/New AGS0 since all of them are excellent looking. Obviously, AGS eventually saw a ''problem'' with the steep/steep and thus decided to excluded them from the ''New'' AGS0 criteria. What was their ''official'' justification for this change in position? Based on what?

Hi Midnight,

This is an area I like about the AGS system over the GIA. I like the more critical anlaysis and the elimination of leakage under the table when it comes to cut grading. This is my personal preference with regards to cut grading. GIA however chose to base their cut grading on human observation and factors that is what influenced their cut grade.

I have found that ...

GIA is more conservative on the shallow/shallow combinations (since they impact face up appearance) while AGS is more conservative on the steep/deep combinations since they contribute to leakage under the table as observed under ASET.

So in short it is based on leakage factors examined in the critical analysis.

 

[tarssarb]

Hi,

Ok, I concede, I see your objective... You were addressing point 4 I believe of the original GIA critisim (painted girdles)? A moderate steep/deep polled better than the painted girdles and thus is included while a very good proportioned painted is exluded. I started a new thread ("brilliance scope of 3 eightstar diamonds") were I think I made some "layman" observations on painting.

I think the major uproar as I read it is that the excellent range is too large. The experiment I suggested would be insightful on addressing this.

So say a 57 Table with 34.5/41.6 compared to a 34.5/40.8. This would be a test if GIA should have included steep/deep and would also imply about the correctness of the EX grade tolerance.

 

[Rhino]

Hi Serg,

Date: 3/12/2006 1:26:31 AM
Author: Serg

Rhino,

1)Please inform about consumer tests this stones in normal light condition( not DD GIA) , for example in your office light. Result will quite different.

Unfortunately we can not bring clients behind the counter and into our offices. Results are same though. Please see the pic I posted in natural daylight.

Date: 3/12/2006 1:26:31 AM
Author: Serg

DD is penalty all nice diamonds without leakage. If you want understand why please read https://www.pricescope.com/community/threads/how-lighting-can-influence-on-grade-appearance.38583/=

I''ll check this out first opportunity. As I had mentioned earlier in this thread, this phenomena is not limited to the DiamondDock Serg.

I would make this exception however. When viewing a diamond with a painted girdle the darkness is not apparent in reflected light conditions. Ie. if the primary light sources are coming from windows, reflecting off of walls, this is the best environment to view the aspect of optical symmetry and in these environments, stones with painted girdles appear equal to classic ideal girdles. Otherwise in more common lighting environments it can be seen.

Date: 3/12/2006 1:26:31 AM
Author: Serg

2) If you really want understanding How is GIA system correct? To Take GIA EX with Pav 41.6/Pav34.5 on normal light conditions . This diamond are pointing to GIA cut grade mistake.

When I get that kind of stone in hand I will be happy to give my professional opinion and solicit consumer input as well. I''m not going to criticize something I haven''t personally inspected. Considering the testing I have just completed, I have to give GIA the benefit of the doubt. I did not expect the results I got with this one Serg even though my personal preferences have always lied with a non-painted stone.

3) Pav 41.2 Cr 35 is really nice stone. It has not death ring in stereo vision. This diamond are pointing to AGS cut grade mistake( I told it on PS several months ago)

LOL... I happen to agree with you now. However this advice runs counter to what many are saying here. I can''t think of a person here who would EVER recommend the GIA Ex over the AGS ideal in this case. Besides the darker issue of the painted girdle I have some thoughts as to why the other was so bright. I think Mike hit on some of it but I gotta read what he wrote. I''ll try and catch up on this tomorrow.

It is pity see your choice diamonds and light conditions for consumer tests. After your post I start think to Back to help developing cut grade system. ( Earlier I thought : Market will reject wrong GIA cut grade system without any my efforts. Now I see my work is necessary to market yet )

Serg... my goal was to understand their system and how they arrived at the conclusions they have. I totally understand it and the logic and science behind it as well. They don''t go into as critical an analysis as I would have liked to see but they did lay the boundaries that define their system and the evidence I have gathered so far only confirms the veracity of it so far. I totally understand why both painted and dug out girdles take the hit and so do most of the consumers who made the observations.

I always look forward to your input Serg and will read your link at my earliest.

Kind regards,
Jonathan

 

[adamasgem]

Date: 3/13/2006 12:09:40 AM
Author: Rhino

It is pity see your choice diamonds and light conditions for consumer tests. After your post I start think to Back to help developing cut grade system. ( Earlier I thought : Market will reject wrong GIA cut grade system without any my efforts. Now I see my work is necessary to market yet )

Serg... my goal was to understand their system and how they arrived at the conclusions they have. I totally understand it and the logic and science behind it as well. They don''t go into as critical an analysis as I would have liked to see but they did lay the boundaries that define their system and the evidence I have gathered so far only confirms the veracity of it so far. I totally understand why both painted and dug out girdles take the hit and so do most of the consumers who made the observations.

I always look forward to your input Serg and will read your link at my earliest.

Kind regards,
Jonathan

Jonathan.. I fail to see how the DiamondDocK light source would correlate at all with what they SAID they did use for their basic brightness metric, a 23 deg (46 total angle) obscured hemisphere, since the primary lighting in the DD is from above from what I assume are two 15 watt fluorescent daylight tubes.

I''d like to see what the intensity measurements (Lux) are.. and also what the preference results would be cutting out the glare..

So we have an largely undefined "preference based" cut grade system tailored, or heavily weighted, to their observation data and their light source..

 

[Garry H (Cut Nut)]

Rhino like me you have a lot of reading to do on this link https://www.pricescope.com/community/threads/how-lighting-can-influence-on-grade-appearance.38583/ that Sergey sent you.

I am somewhat surprised to learn that you show consumers diamonds under any sort of desk lamp.
I believe diamopntaires consume ALMOST ALL THE WORLDS DESK LAMPS.

GIA designer Diamond Dock to replicate a dealers environment - but this envioronment evolved out of necessity for color and clarity grading.

As you will discover in Sregey''s thread above - the close proximity of fluoro lights to a diamond plays all sorts of havock with our eyesight and perception.

It might be time to stop and think.

I have studied a diamond that is is steep deep under Diamond Dock. Some people have seen the first drafts and some photo''s - but my life has been a little hectic - will try to have a late night tonight and get a copy to Leonid for a Journal articvle.

over and out

 

[RockDoc]

I am a little surprised at the results from consumers that Rhino has tranmitted in this thread.

I find it hard to believe that everyone rendering an opinion made it favoring one stone or the other.

I find that novice eyes, have a bit of understanding their preferences at first, so I am sort of surprised no one said

a) I don''t like either stone

b) I like both stones they both look the same to me

c) I can''t really separate which I like better


I would think that at least one in the 23 people would have answered a, b or c above.


Rockdoc

 

[adamasgem]

Date: 3/12/2006 8:02:15 PM
Author: Rhino

GIA does not own me Marty. I resent you saying and suggesting that my opinion can be bought or that I am trying to kiss butt. I guess I''m trying to kiss AGS''s butt too because I am seeking membership in their organization?

Gee, they "own" most of the rest of the industry, whatever GIA says is the gospel according to Saint GIA. Here is our cut grading system and here is our patented $1.6K light source that "proves" it, what ever "it" is.

And you apparently bought right into it.

You know me, I call it like I see it, based on what has been said now and in the past on other threads, point out and question the inconsistencies of which their are many when one is "learning", and let the chips fall where they may. Sometimes my sarcasm is wrongly placed, if it is, I appologise.

As to AGS membership, maybe it would be very informative to you..

By the way, regarding painted girdles and optical symmetry, you are aware of course, that both contribute to less internal light absorption so that the overall faceup bodycolor of a well cut stone seems to be apparently better than what the "color grade" would suggest. By the way, what were the color grades of the two stones you used in your test. I''ll check back on the first pages and edit this if I can find it.

Still like ya though... I''ll ask Todd what he thinks since you quoted him..

 

[RockDoc]

In an earlier post in this thread, I read the statement that "diamonds are equally transparent"


Maybe I am the "black sheep" on this subject - but I can see sometimes great differences of tranparency levels between many diamonds.

Was that you that wrote that Rhino, or was it Mike Cowing?

Rockdoc

 

[Serg]

re:I''ll check this out first opportunity. As I had mentioned earlier in this thread, this phenomena is not limited to the DiamondDock Serg.

I would make this exception however. When viewing a diamond with a painted girdle the darkness is not apparent in reflected light conditions. Ie. if the primary light sources are coming from windows, reflecting off of walls, this is the best environment to view the aspect of optical symmetry and in these environments, stones with painted girdles appear equal to classic ideal girdles. Otherwise in more common lighting environments it can be seen.

Rhino,

I think you mixed two phenomena.
1) Diamonds without leakage( and some other diamonds too) is darker under DD GIA or similar light conditions.( In same such diamonds are beautiful in normal CONSUMER light conditions
2) Painted diamonds

Please read and understand Topic "How lighting can influence on grade appearance"

Firstly You need understand Why nice diamond can be very dark in "Professional light scheme". Then we can discuss about GIA, AGS, cut grading systems and about painted diamonds.

 

[Shay37]

Date: 3/12/2006 6:41:02 PM
Author: Rhino
You know what I love about you Marty ... you''re like me in many regards. A natural born skeptic.

Date: 3/11/2006 3:34:41 PM
Author: adamasgem

Out of 25 observers in total so far, 23 picked the GIA Ex in l.e.d. lighting and 23 picked the GIA Ex in daylighting, I kid you not!

I was thrown for a loop with this research!

No surprise there, you can design an envirionment to mask differences, that is all..

Do you feel this phenomena is *only* observable under a GIA DiamondDock? If you recall earlier in this thread I stated rather clearly that if the DD did not emulate natural lighting I would have returned it. While I do not have a photograph on my harddrive of the 2 comparison stones in this study, here is one I took of 2 diamonds, same size, virtually identical angles and table, only difference ... one painted and one not. Attached is that photo taken in natural daylight. No ''custome designed'' or ''rigged'' environment to flatter one and not the other. I was sitting on my porch in natural daylight. The same phenomena is observable no matter what daylight conditions you commpare the diamonds in, I would note with the exception of an environment that is primarily reflective light as opposed to brighter direct light. Didn''t I also state rather clearly that I first showed observers in natural daylight coming in from our window and when the reported results were identical each and every time, only then did I stick to the DiamondDock? Come on now Marty.

All the best,
Jon

Okay, here is where I have to split hairs with you. This muddies the water a bit for people who might be just scannning and think that the pic is the two stones in the survey. BTW, why not post a pic of the two stone just like that mounted (fake mount) and obviously not in the DD. It may not be the best way to judge a stone, but you thought this pic was good enough for comparison.

The pic you posted does not help it only confuses cause I know darn good and well your ring is not a steep/deep.

shay

 

[Serg]

re:While I do not have a photograph on my harddrive of the 2 comparison stones in this study, here is one I took of 2 diamonds, same size, virtually identical angles and table, only difference ... one painted and one not. Attached is that photo taken in natural daylight. No ''custome designed'' or ''rigged'' environment to flatter one and not the other. I was sitting on my porch in natural daylight.


Rhino,

1)PLease published 3D models for exactly this 2 stones( from your photo).
2) PLease confirm : It are not stones from your tests 23 consumers

Shay, Thank you.

 

[Serg]

re:LOL... I happen to agree with you now. However this advice runs counter to what many are saying here. I can''t think of a person here who would EVER recommend the GIA Ex over the AGS ideal in this case. Besides the darker issue of the painted girdle I have some thoughts as to why the other was so bright. I think Mike hit on some of it but I gotta read what he wrote. I''ll try and catch up on this tomorrow.




see: https://www.pricescope.com/community/threads/an-ags-view-of-gia-steep-deep-excellent.32764/



Serg

Ideal Rock

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re: But would you pay top dollar for the steep/deep stone?

I am ready pay 90-95% from top dollar. May be I will pay 95-100%

I see only one objective reason for discount now. It is spread



Revisions : 0 | Posted: 8/28/2005 10:29:48 AM |


re:But if you looked at a steep deep from 14 to 15 inches 350 cm - this is the leaakage you would see in a GIA Excellent AGS 5 stone seen with 5 degrees of tilt.
But Your brain could do not see leakage for T57P41.2Cr34.5=AGS4,
Right eye will see bright zone in left side and dark zone ( leakage in IS) in right side table in normal light condition.
Left eye will see bright zone in right side and dark zone ( leakage in IS)in left side table in normal light condition.

If bright zones are more bright than level of eye adaptation( like usually), your brain can not see dark ring in table

 

[Lynn B]

Very interesting discussion.

Is there any way for a layperson to know if their AGS-0 stone has a painted girdle?

Thanks,
Lynn

 

[Paul-Antwerp]

I was reading this and other threads with a lot of interest. Here are my thoughts:

First, I find it appalling how some people react here in such a personal manner. It sure tells you more about the writer than about the content of that post. May I ask everyone to become less emotional in their replies, and more to the fact. In this way, it does not fit us to accuse Jonathan of butt-kissing or ulterior motives, and he may have made a mistake in his observations, there are definitely more adult ways of finding the truth.

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.

So, here our theory is not confirmed by practice. Water seems to be running uphill.

My first question: did the GIA-EX receive a second grading by AGS, and what are the results? Did the AGS-0 get a second grading by GIA, and what are the results?

Second question: I am absolutely convinced that Jonathan performed this testing in the most equitable way. Now, could there have been a mistake? This might be interesting, since we tend to learn more from our mistakes, than from what we do correctly.

Third question: Is the difference between the two kinds of stones big enough to warrant one to be downgraded one or two layers in a 5-layer-system? If that is the case, since I do not know the answers to question 1.

Just trying to bring us back to the basics.