Some movement on GIA "Painting.”

[JohnQuixote]

Literal movement; not a change in assessment.

Starting today, GIA plans to move the placement and wording of the comments “Cut grade is based on brillianteering of the half-facets.” It will be moved away from the comments section and underneath the proportion diagram, and edited to “Cut grade affected by brillianteering.” This is so readers can understand this comment is related to GIA's evaluation of cut. The lab will provide a re-issue service for a 3 months period for any reports that have the original brillianteering comment in the comments section.

No word yet as to refinement of the evaluation process, apart from what was reported at the conclusion of the JCK convention. The lab’s feeling is that diamonds submitted today, as opposed to several months ago, are being more decisively evaluated. There was a lot of buzz and confusion some time ago: Reactions were strong because initial impressions were based on Report Check (which had glitches when introduced) and earliest grading, which has since been fine-tuned. Ongoing discussions with GIA indicate that diamonds of the type commonly seen on PS would not receive penalties for brillianteering; specifically painting. More to come.

 

[whatmeworry]

JQ,

What is your understanding of the fine-tuning? Is it an actual numerical deviation that is measured and the cut grade is then affected based on the degree of the deviation from normal?

Is any downgrade based on human observation testing or is it based on running their computer simulations and looking at the brilliance/fire metrics?

Just saying that lab feels that diamonds are being more "decisively evaluated" today doesn''t seem very authoritative.

P.S. I don''t want to start another painting or AGS vs GIA cut thread. Just want to know what the fine-tuning is.

 

[strmrdr]

wow they haven''t caved in yet I''m shocked.
The system was made loose enough for the weight is everything crowd why not cave in to the painting crowd.

 

[JohnQuixote]

Date: 7/1/2006 7:10:14 PM
Author: whatmeworry
JQ,

What is your understanding of the fine-tuning? Is it an actual numerical deviation that is measured and the cut grade is then affected based on the degree of the deviation from normal?

Is any downgrade based on human observation testing or is it based on running their computer simulations and looking at the brilliance/fire metrics?

Just saying that lab feels that diamonds are being more 'decisively evaluated' today doesn't seem very authoritative.

I was not told what the fine-tuning was specifically, just that the system has been improved since launch. That information is from the clarification I was given at JCK and follow-up since then. The only authoritative statement above regards the movement of the comment to the plot.

To answer your question, you've got it; a flat numerical evaluation is used. Remember that GIA is not performing 3D computer simulations for brightness, etc. (that's AGS). GIA does Sarin/Scan measurements and uses the rounded average proportions for the broad cut grade. Human observers check polish/sym. Sarin numbers are used for a brillianteering judgment. So, no face-up assessment is made on individual diamonds for brillianteering, nor human observation. They cite prior, cumulative observations to support the flat number. This is where we depart in methodology, because they take one value and apply it to all diamonds, whether steep/shallow or Tolkowsky.

The good thing is that their numerical evaluation is wider than first thought/calculated based on RC and early grading. The questions that remain unanswered revolve around flat use of these numbers for all diamonds in the future (?)

P.S. I don't want to start another painting or AGS vs GIA cut thread. Just want to know what the fine-tuning is.

Righto. You and about 101 other Pricescopers who are getting their tar and feathers out as they read this.

For some light reading, here is a techie discussion on interpreting this aspect of brillianteering in a way that's not stereotyping. Thanks for the query.

https://www.pricescope.com/community/threads/why-would-anyone-object-to-painting.45579/page-4

 

[Rhino]

Date: 7/1/2006 8:06:17 PM
Author: JohnQuixote

Date: 7/1/2006 7:10:14 PM
Author: whatmeworry
JQ,

What is your understanding of the fine-tuning? Is it an actual numerical deviation that is measured and the cut grade is then affected based on the degree of the deviation from normal?

Is any downgrade based on human observation testing or is it based on running their computer simulations and looking at the brilliance/fire metrics?

Just saying that lab feels that diamonds are being more ''decisively evaluated'' today doesn''t seem very authoritative.

I was not told what the fine-tuning was specifically, just that the system has been improved since launch. That information is from the clarification I was given at JCK and follow-up since then. The only authoritative statement above regards the movement of the comment to the plot.

To answer your question, you''ve got it; a flat numerical evaluation is used. Remember that GIA is not performing 3D computer simulations for brightness, etc. (that''s AGS). GIA does Sarin/Scan measurements and uses the rounded average proportions for the broad cut grade. Human observers check polish/sym. Sarin numbers are used for a brillianteering judgment. So, no face-up assessment is made on individual diamonds for brillianteering, nor human observation. They cite prior, cumulative observations to support the flat number. This is where we depart in methodology, because they take one value and apply it to all diamonds, whether steep/shallow or Tolkowsky.

The good thing is that their numerical evaluation is wider than first thought/calculated based on RC and early grading. The questions that remain unanswered revolve around flat use of these numbers for all diamonds in the future (?)

Hi John,

Thanks for the info.

Question: Exactly which numbers from the Sarin scan were you told they are using to determine the degrees of painting?

 

[Paul-Antwerp]

I read John''s post about three times now, and I think that it unclear in the following way. However, it could just as well be the fact that English is not my mother-tongue.

Anyway, John''s post gives the impression that the downgrading of painting is based upon Sarin-figures, but if I re-read it, it is not clear that he actually says this. John, could you clarify?

My impression anyway was that downgrading was based upon visual assessment of the girdle.

And having worked in a diamond-cutting factory with 1200 workers in the beginning of my career, I know that instructing people on visual observations always gives exaggerated results right after a change in a system.

Live long,

 

[RockDoc]

Thanks John.

I sort of wonder if Facetware, will be adjusted especially with so many people who have Sarin''s also have the Facetware program.

Personally, I don''t see that this will be, or better yet, how it can be incorporated into the system, and will be misleading reports that will be generated to many consumers who will be relying on the results supplied by sellers.

For consumers, I guess I''d advise them to purchase diamonds from those like WF,Infinity just to name two ( there are undoubtledly more sellers) who exclusively get the AGS report for the stones they cut or offer for sale.

I''ve also been reading the latest GIA Insider issue, about evaluating images in the Diamond Dock relevant to the H&A image.
Seems to be some rather meaningless and misleading info there. I found nothing about the hearts evaluation of a stone, and only saw comment about the arrows, which appears to be a "tad" incorrect.

Does the term "atheletes mouth" seem apparent to you too? Brian must be self destructing after reading that article.

Rockdoc

 

[RockDoc]

John

Surprised we didn''t hear from you here.

Rockdoc

 

[JohnQuixote]

Hi guys.

Sorry Rockdoc, but I was having a Sunday away from the computer.

Date: 7/2/2006 6:59:50 AM
Author: Paul-Antwerp

John's post gives the impression that the downgrading of painting is based upon Sarin-figures, but if I re-read it, it is not clear that he actually says this. John, could you clarify?

My impression anyway was that downgrading was based upon visual assessment of the girdle.

The question has had different answers. First, in April, this article from GIA indicated visual assessment as the most direct way to determine painting... But then in June I was told that such visual assessment is for proprietary grading, away from the lab. They say that in the lab the Sarin scan is used as a primary means of making angular assessment and determining degree of painting.

(Paul, I gave that info in this post, but I believe you were still traveling at the time it was posted.)

Rhino, on your question, I don’t have the recipe for the whole cake, but the prime ingredient appears to be indexing of the halves. I have been given a flat tolerance for average azimuth deviation (upper halves only) but don’t have permission to publicize it. It may not be a big deal, but I’d rather err on the side of etiquette. We’re due to speak again this week and I’ll get as much info as they are willing to provide.

Hope everyone had a nice weekend.

 

[JohnQuixote]

Date: 7/2/2006 10:19:28 AM
Author: RockDoc
Thanks John.

I sort of wonder if Facetware, will be adjusted especially with so many people who have Sarin''s also have the Facetware program.

Personally, I don''t see that this will be, or better yet, how it can be incorporated into the system, and will be misleading reports that will be generated to many consumers who will be relying on the results supplied by sellers.

For consumers, I guess I''d advise them to purchase diamonds from those like WF,Infinity just to name two ( there are undoubtledly more sellers) who exclusively get the AGS report for the stones they cut or offer for sale.

I''ve also been reading the latest GIA Insider issue, about evaluating images in the Diamond Dock relevant to the H&A image.
Seems to be some rather meaningless and misleading info there. I found nothing about the hearts evaluation of a stone, and only saw comment about the arrows, which appears to be a ''tad'' incorrect.

Does the term ''atheletes mouth'' seem apparent to you too? Brian must be self destructing after reading that article.

Rockdoc

Hey Rock, so as not to confuse topics I''ll start a new thread about the Insider article.

 

[Garry H (Cut Nut)]

Date: 7/2/2006 10:53:42 PM
Author: JohnQuixote
Rhino, on your question, I don’t have the recipe for the whole cake, but the prime ingredient appears to be indexing of the halves. I have been given a flat tolerance for average azimuth deviation (upper halves only) but don’t have permission to publicize it. It may not be a big deal, but I’d rather err on the side of etiquette. We’re due to speak again this week and I’ll get as much info as they are willing to provide.

Hope everyone had a nice weekend.

I had a bit of a chat to Phil Yantzer (West Coast lab director) about this issue and as i recall the answer is that GIA use the average % diference between the minor and main facet junction girdle thickness to determine the amount of painting or digging. He would not give me a quantitative guide, but noted that the graphics GIA published did perhaps have too large a ''gap'' between Excellent and Very good (You might remeber Sergey quantified this as something like Excellent was 0-1 degrees of azimuth, VG was 1-5, Good was about 7 and 9 for fair poor - as i remeber).

Sergey is changing the reporting method on Helium etc to azimuth variation because it is a much more sensitive number to use.

GIA still remind us that they do not use Sarin to assess girdle thickness - that is done with the human eye and judgement - which they believe is more accurate than Sarin.