GIA on Painting and Digging

[pricescope]

From the GIA Laboratory: Visually Estimating Painting and Digging Out in Standard Round Brilliant Diamonds

or download a pdf of this article with high resolution images

 

[FireGoddess]

Thanks for the heads up! I love educational articles about diamonds....and have wanted to know more about painting.

 

[strmrdr]

bout what I expected.
if its easily visible on the girdle it gets downgraded.
since a lot of the low end scanners wont see it at all and they are geared to the lowest of the low end devices with the rounding so a visual check fits the system.

 

[JohnQuixote]

Thanks for posting this Leonid.

It’s useful to see the diagrams, but it’s another example of GIA’s mass-grading approach. They are stereotyping with a simple profile assessment. This is not useful because such a check doesn’t tell the story with regard to light performance.

The level of what’s appropriate depends entirely on overall configuration. Pavilion main angle, lower girdle length, crown main angle, star length and table size all figure into the equation. This is why painted and traditional diamonds alike can earn the AGS 0 grade in light performance. Extremes should be penalized in either approach, but when cutting proportions near Tolkowsky a degree of painting is perfectly safe. The direct-assessment performed by the AGS confirms this, as do thousands of owners of premium diamonds finished in this manner.

GIA says: "Although we have found that painting and digging out affect the cut grades of only a small percentage of diamonds submitted to the GIA Laboratory, they are a factor in the GIA Diamond Cut Grading System and individuals should familiarize themselves with these brillianteering methods."

This may serve mass-manufacture, but it’s wrong to stereotype all diamonds as behaving one way due to girdle profile.

Message to GIA: Although painting and digging out affect only a ‘small percentage of diamonds,' a fraction of your ‘small percentage’ happen to be some of the most carefully cut, top performing diamonds on earth. Mass-grading approaches like this, and rounding, do not serve the manufacturers, science professionals, sellers and buyers who seek grading precision and accuracy.

 

[JohnQuixote]

Other recent threads re GIA's cut grading system/DiamondDock.

Garry, perhaps you will add this one to the list?

 

[Garry H (Cut Nut)]

Date: 4/28/2006 10:56:08 PM
Author: JohnQuixote
Other recent threads re GIA''s cut grading system/DiamondDock.

Garry, perhaps you will add this one to the list?

John you first post makes an excellent case.
History -
1. GIA released a newsletter story a couple of years back which made it clear they did not like 8* and favoured digging. I said that at the time and everyone said no- that was not the hidden message.
2. this recent article Leonid linked to was published last year in Rapaport hard copy mag.

The trouble with painitng and digging is as you say John
"The level of what’s appropriate depends entirely on overall configuration. Pavilion main angle, lower girdle length, crown main angle, star length and table size all figure into the equation."

Add to that that painitng and digging add a variability that is about 5 times as much impact as minor facets for each of the 6 vairiables. Paint upper or lower, dig upper or lower, and then the 2 possible combinations. This makes the 38.5 million data point survey 38,500,000 to the power of 6to the power of the number of degrees of azimuth shift you select (say 3 or 5?). The survey in Diamond Dock will now take 1,000years to complete in oredr for GIA to grade painting and digging.

not do-able.

BTW in reference to the hugely impressivve 38.5 million data points - HCA has the following number of data points:
350x120x25x140x100 = 20,580,000,000
Does that mean HCA is 53.45 times better than GIA Facetware?

 

[Rhino]

Hi guys,

I think the wisest counsel to offer consumers on this issue is quite simple. If they are going to consider a diamond that departs from either AGS or GIA''s top cut grade, that they should indeed see and compare that stone to the top cut grade and make an intelligent and informed decision for themselves unless they otherwise insist on the blind purchase.

Also to state what degree of painting/digging is acceptable/unacceptable is not for any one trade member to determine. If the end consumer is desiring a top cut quality grade and is considering departing from either labs standards for such, I say let the consumer see and decide for themselves. Otherwise the safest counsel for the Internet consumer is stick to stones that fall into both labs requirements for top grades and educate them on the differences in appearance should they decide to depart from those standards.

Peace,

 

[Garry H (Cut Nut)]

Date: 4/29/2006 2:46:55 PM
Author: Rhino
Hi guys,

Also to state what degree of painting/digging is acceptable/unacceptable is not for any one trade member to determine. If the end consumer is desiring a top cut quality grade and is considering departing from either labs standards for such, I say let the consumer see and decide for themselves. Otherwise the safest counsel for the Internet consumer is stick to stones that fall into both labs requirements for top grades and educate them on the differences in appearance should they decide to depart from those standards.

Peace,

And pray tell Rhino, does this mean duplicate grading by both labs?

If we were talking about grading by proportions alone then a consumer could use the data on the cert''s (although GIA''s rounded data makes using AGS candidate numbers very rough) and enter them onto HCA and they can see the candidate likelyhood.

But this thread we are talking about how gIA grades painting and digging Rhino.

I do not think this game is so easy to play?
Let me ask you to offer a grade for this stone please from both labs?

 

[Garry H (Cut Nut)]

Oops - here is the GIA report info

 

[Rhino]

Date: 4/29/2006 4:20:25 PM
Author: Garry H (Cut Nut)

Date: 4/29/2006 2:46:55 PM
Author: Rhino
Hi guys,

Also to state what degree of painting/digging is acceptable/unacceptable is not for any one trade member to determine. If the end consumer is desiring a top cut quality grade and is considering departing from either labs standards for such, I say let the consumer see and decide for themselves. Otherwise the safest counsel for the Internet consumer is stick to stones that fall into both labs requirements for top grades and educate them on the differences in appearance should they decide to depart from those standards.

Peace,

And pray tell Rhino, does this mean duplicate grading by both labs?

If we were talking about grading by proportions alone then a consumer could use the data on the cert''s (although GIA''s rounded data makes using AGS candidate numbers very rough) and enter them onto HCA and they can see the candidate likelyhood.

But this thread we are talking about how gIA grades painting and digging Rhino.

I do not think this game is so easy to play?
Let me ask you to offer a grade for this stone please from both labs?

If I can physically inspect the diamond here in my lab I can do it. I''ve seen enough diamonds now to know what and what isn''t going to make the grade with regards to painting/digging. Send me the stone and I''ll be happy to oblige.

 

[Garry H (Cut Nut)]

Date: 4/30/2006 5:20:26 PM
Author: Rhino

Date: 4/29/2006 4:20:25 PM
Author: Garry H (Cut Nut)

Date: 4/29/2006 2:46:55 PM
Author: Rhino
Hi guys,

Also to state what degree of painting/digging is acceptable/unacceptable is not for any one trade member to determine. If the end consumer is desiring a top cut quality grade and is considering departing from either labs standards for such, I say let the consumer see and decide for themselves. Otherwise the safest counsel for the Internet consumer is stick to stones that fall into both labs requirements for top grades and educate them on the differences in appearance should they decide to depart from those standards.

Peace,

And pray tell Rhino, does this mean duplicate grading by both labs?

If we were talking about grading by proportions alone then a consumer could use the data on the cert''s (although GIA''s rounded data makes using AGS candidate numbers very rough) and enter them onto HCA and they can see the candidate likelyhood.

But this thread we are talking about how gIA grades painting and digging Rhino.

I do not think this game is so easy to play?
Let me ask you to offer a grade for this stone please from both labs?

If I can physically inspect the diamond here in my lab I can do it. I''ve seen enough diamonds now to know what and what isn''t going to make the grade with regards to painting/digging. Send me the stone and I''ll be happy to oblige.

So we need not trust labs rhino - just your eyes?

Do you think on your website you should probably change the terminology to "candidate" rather than indicating an actual grade on a stone when the labs have not actually graded that diamond?

 

[Garry H (Cut Nut)]

And BTW the stone got graded GIA Poor even though the proportions in Facetware show Excellent Candidate downgraded to Very Good because of Sym and Polish.

 

[adamasgem]

Date: 4/28/2006 10:51:20 PM
Author: JohnQuixote

Thanks for posting this Leonid.

It’s useful to see the diagrams, but it’s another example of GIA’s mass-grading approach. They are stereotyping with a simple profile assessment. This is not useful because such a check doesn’t tell the story with regard to light performance.

The level of what’s appropriate depends entirely on overall configuration. Pavilion main angle, lower girdle length, crown main angle, star length and table size all figure into the equation. This is why painted and traditional diamonds alike can earn the AGS 0 grade in light performance. Extremes should be penalized in either approach, but when cutting proportions near Tolkowsky a degree of painting is perfectly safe. The direct-assessment performed by the AGS confirms this, as do thousands of owners of premium diamonds finished in this manner.

GIA says: ''Although we have found that painting and digging out affect the cut grades of only a small percentage of diamonds submitted to the GIA Laboratory, they are a factor in the GIA Diamond Cut Grading System and individuals should familiarize themselves with these brillianteering methods.''

This may serve mass-manufacture, but it’s wrong to stereotype all diamonds as behaving one way due to girdle profile.

Message to GIA: Although painting and digging out affect only a ‘small percentage of diamonds,'' a fraction of your ‘small percentage’ happen to be some of the most carefully cut, top performing diamonds on earth. Mass-grading approaches like this, and rounding, do not serve the manufacturers, science professionals, sellers and buyers who seek grading precision and accuracy.

John..
This is just another example of GIA''s arbitrary, non performanced based, FARCEWARE practice.. market manipulation, to suit the mass merchandisers and the hell with the consumer who wants selectivity of the very best..

 

[adamasgem]

Date: 4/29/2006 9:57:10 AM
Author: Garry H (Cut Nut)
''The level of what’s appropriate depends entirely on overall configuration. Pavilion main angle, lower girdle length, crown main angle, star length and table size all figure into the equation.''

Add to that that painitng and digging add a variability that is about 5 times as much impact as minor facets for each of the 6 vairiables. Paint upper or lower, dig upper or lower, and then the 2 possible combinations. This makes the 38.5 million data point survey 38,500,000 to the power of 6to the power of the number of degrees of azimuth shift you select (say 3 or 5?). The survey in Diamond Dock will now take 1,000years to complete in oredr for GIA to grade painting and digging.

not do-able.

BTW in reference to the hugely impressivve 38.5 million data points - HCA has the following number of data points:
350x120x25x140x100 = 20,580,000,000
Does that mean HCA is 53.45 times better than GIA Facetware?

By GIA''s logic and sales pitch reasoning, DEFINATELY..