Laboratory Cut Grades: What the report doesn’t show

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Laboratory Cut Grades: What the report doesn’t show

http://journal.pricescope.com/Articles/72/1/Laboratory-Cut-Grades-What-the-report-doesn%e2%80%99t-show.aspx

by John Pollard



Thank You John!

 

[oldminer]

Great article. The combinaton of the excellent photos under controlled lighting along with the various optional assessment tool images is a real piece of work. Very informative. Many of us look forward to solid cut grading being available for all the standard shapes. It is a good goal for us to work toward.

 

[denverappraiser]

John,

Great work as always. Thanks for the contribution.

Neil Beaty
GG(GIA) ICGA(AGS) NAJA
Professional Appraisals in Denver

 

[strmrdr]

Bravo!

You can say this 3 times!

It is certain that consumers are not becoming less educated. Tomorrow’s shoppers will be even more data-intensive and detailed than today’s. As our public evolves in their expectations our trade must evolve in terms of communication. With that in mind I urge industry professionals to be proactive in developing strategies to better serve a growing, more demanding, better-educated public.

 

[John P]

Date: 5/26/2009 12:41:26 PM
Author: oldminer
Great article. The combinaton of the excellent photos under controlled lighting along with the various optional assessment tool images is a real piece of work. Very informative. Many of us look forward to solid cut grading being available for all the standard shapes. It is a good goal for us to work toward.

Thanks for the notes gentlemen.

I see a regular pattern of consumers coming aboard this forum, presuming diamonds with the same cut grade will have identical appearance. And why shouldn''t they? It''s the way the other C''s are treated; at least at the top.

One can see the differences in live situations - IFF different lighting is employed & different makes are present to be seen. I applaud the traditional stores who carry a variety of inventory and show it side by side in different lighting situations. For those doing internet research and buying communication is a larger task. Fortunately in a place like PS there are dedicated regulars "in the trenches" helping with that communication in a number of ways... But you''re right Dave, we need to work for more.

 

[Rockdiamond]

Great article John!

Date: 5/26/2009 12:41:26 PM
Author: oldminer
Great article. The combinaton of the excellent photos under controlled lighting along with the various optional assessment tool images is a real piece of work. Very informative. Many of us look forward to solid cut grading being available for all the standard shapes. It is a good goal for us to work toward.

Maybe it''s because if the fact that we deal in a lot of unusual shapes and colors- but I for one think that trying to somehow "define" what is beautiful in fancy shapes is totally counterproductive.

Looking at the differences between near tolk, as compared to larger tabled rounds I see an industry prejudice toward smaller tables. I realize that AGS and GIA do include some of the larger tabled combinations in the top grade- but both are biased towards the type of light performance that smaller tables produce.
There are certainly VG cut grades, or 1-2-3 AGS cut grades that perform differently than the smaller tabled stones.
Some viewers will prefer over these over the smaller tabled EX, or 0 cut grade.
Rounds are by far the most "standardizable" shape- but for these reasons, calling one "better" than the other is ignoring many people''s subjective assessment.

If we''re going to try and do the same with Cushions, for example, it''s bound to favor one type of stone over another. Clearly, some people like a more antique look, while others go for a more modern facet pattern. Who''s right?

 

[John P]

Clarification for GIA Facetware users:

It was communicated to me that one should select Girdle Thickness in Facetware rather than Depth% for accurate results. Using Depth% instead of GT can produce a different result in Facetware than the grade that was issued at the lab.

 

[strmrdr]

We have discussed looks vs performance vs preference to death in a 100 other threads.
I think John has earned being shown the respect to keep this thread about his article.

 

[Lula]

Thank you for compiling and presenting this excellent information, John! As a consumer who is currently shopping for a diamond, this is one of the most useful things I''ve read on Pricescope. What a great tool to use when looking at an IS or ASET online and trying to estimate (along with the numbers) what it might look like "live." I know nothing can replace an in-person 3-D inspection in different lighting conditions, but this does help a newbie like me get some idea of how many different "looks" ideal/ex cut diamonds can have. Thanks again!

One question, is the photo of diamonds 1 and 2 in someone''s hand a comparison between two smudgy, dirty diamonds?

 

[John P]

Date: 5/26/2009 6:00:46 PM
Author: sarap333
Thank you for compiling and presenting this excellent information, John! As a consumer who is currently shopping for a diamond, this is one of the most useful things I've read on Pricescope. What a great tool to use when looking at an IS or ASET online and trying to estimate (along with the numbers) what it might look like 'live.' I know nothing can replace an in-person 3-D inspection in different lighting conditions, but this does help a newbie like me get some idea of how many different 'looks' ideal/ex cut diamonds can have. Thanks again!

One question, is the photo of diamonds 1 and 2 in someone's hand a comparison between two smudgy, dirty diamonds?

I'm glad to know the article is already serving that purpose Sarap. The highlighted is the fundamental reason I thought such a piece to be necessary.

I want to give credit to the great photographers who did those many photos. You're right, the diamonds in the skin shots may have smudes - I suspect b/c this was not a normal request. It was a "bonus" shot I requested as another way of showing how the facets of one diamond can act as windows (skin visible underneath) while the facets of another can act as mirrors (skin not visible). This influences the pattern of light return & contrast.

While this can also be seen against black backgrounds, also in Section D, the skin shot is a kind of PS "tradition."

 

[asforhim]

GREAT ARTICLE! It very nicely illustrates why it is so important to see diamonds in person before purchasing. Many of the diamonds shown with less than
"perfect" ASET results actually perform much better in the "by the naked eye" photos. Consumers should recognize that diamonds with exceptional light characteristics and proportions may not "perfom" as well as those without. I personally own diamonds with excellent cut grades by the GIA and great light performance by ASET that don''t perform nearlly as nice as ones with good or very good cut grades (mostly due to less than perfect polish and symmetry). This is one reason why high end retailers (Graff, HW, etc) shy away from letting the consumer see GIA reports.

 

[Indira-London]

Bravo John - a great article!
Useful for both consumers and professionals: I for one will find very useful in explaining to consumers why some diamonds with the same cut grade look so different from others with the same cut grade!

 

[stone-cold11]

Great article.

Thanks John.

EDT:
John, could you maybe make a note in the expert details about the make. Might be confusing for some. I am guessing NT = Near Tolk and SD = Steep/Deep?

 

[Lorelei]

Kudos my friend, this is a fabulous article!!!!!!!!

 

[Regular Guy]

Ditto my friends, John, a very good article, as usual, helping put into perspective the elements that should be considered as where to start....versus where you might instead be lead in many jewelery stores.

 

[Ellen]

John, as usual, very well written information. Succinct, and in laymens terms for ease of understanding. The pics really are worth a thousand words.. Thank you for taking the time to do this. I see it fast becoming a reference point for those of us trying to help future shoppers.

You sir, are the true definition of a gentleman and a scholar.

(ok, minus all that hair)

 

[Lorelei]

Date: 5/27/2009 8:05:40 AM
Author: Ellen
John, as usual, very well written information. Succinct, and in laymens terms for ease of understanding. The pics really are worth a thousand words.. Thank you for taking the time to do this. I see it fast becoming a reference point for those of us trying to help future shoppers.

You sir, are the true definition of a gentleman and a scholar.

(ok, minus all that hair)

Sir John,

And a jolly good drummer.....

 

[Ellen]

Date: 5/27/2009 9:36:15 AM
Author: Lorelei

Sir John,

And a jolly good drummer.....

<--------- Too cute!

 

[Lorelei]

Date: 5/27/2009 9:45:26 AM
Author: Ellen

Date: 5/27/2009 9:36:15 AM
Author: Lorelei

Sir John,

And a jolly good drummer.....

<--------- Too cute!

Isn''t he though??

 

[Regular Guy]

John, I asked this over there, where it earlier came up, but I am thinking of it here, so will ask it again, and maybe you (or any of your friends) would like to share?

Are there workable tools, do you think, to help with the direct assessment of fire?

 

[jet2ks]

Great article, John! Thanks for writing a very informative piece in ways that many can understand, regardless of level of diamond education.

 

[Garry H (Cut Nut)]

In case you did not notice - selecting stones for this sort of survey is a lot harder than you think.
And there are good and bad 60:60''s

 

[WinkHPD]

Date: 5/27/2009 8:56:19 PM
Author: Garry H (Cut Nut)
In case you did not notice - selecting stones for this sort of survey is a lot harder than you think.
And there are good and bad 60:60''s

John can tell you better than I where he got the various diamonds, but I do know that he spent several days on this article, including a day or two in which he flew to Houston and spent time at WhiteFlash to do the photography.

In addition to being a wonderful article, I think it is a testiment to a wonderful thing about this industry. Here is John who works for Infinity, working with his former employer, WhiteFlash, in a collaborative effort to bring quality information to both the trade and to the public.

Very professionally done and kudos to both John and the photographers at WhiteFlash for working together for every ones mutual benefit!

Wink

 

[Regular Guy]

Date: 5/28/2009 8:48:32 AM
Author: Wink

In addition to being a wonderful article, I think it is a testiment to a wonderful thing about this industry...and some of the special individuals who populate this industry... Here is John who works for Infinity, working with his former employer, WhiteFlash, in a collaborative effort to bring quality information to both the trade and to the public.

Very professionally done and kudos to both John and the photographers at WhiteFlash for working together for every ones mutual benefit!

Wink

I''ll second that.

 

[diagem]

Nicely written article..., chapeau

Now all we need to do is add some more issues Lab''s dont shhhhow

 

[Todd Gray]

This is an excellent article John, as I expected that it would be! The photographs provide excellent insight into how diamonds of similar paper grades for polish and symmetry can exhibit dramatically different levels of optical symmetry and visual performance - something that those of us who hand select our inventory based on these factors have long spoken of and which you have described so well using words (can John write or what? Wow!) and visual examples. As Wink stated, it is so cool that those of us here on PS and in the (very small) world of ideal cut diamonds are able to hang out and get along so well in the school yard! Applause and Accolades to all involved, you''ve put together a wonderful article which will be a great asset to many!

 

[risingsun]

Excellent article, Sir John. Very informative. Well done, sir

 

[John P]

Thanks to everyone for the generous comments and input.

Date: 5/27/2009 6:11:48 AM
Author: Stone-cold11
Great article. Thanks John. EDT: John, could you maybe make a note in the expert details about the make. Might be confusing for some. I am guessing NT = Near Tolk and SD = Steep/Deep?

That's probably a good idea. I added them so peers could see my process of classification. Though softly defined, those monikers are used in the PS lexicon with increasing frequency.

You've got it: NT = Near Tolk, SD = Steep Deep, 60-60 = 60-60. Other round makes could include TR = Transitional, implying small table/high crown (often paired with short lower halves) and SH = Shallow, implying shallower crown & pavilion angles than NT.

Date: 5/27/2009 7:51:23 AM
Author: Regular Guy
John, I asked this over there, where it earlier came up, but I am thinking of it here, so will ask it again, and maybe you (or any of your friends) would like to share?

Are there workable tools, do you think, to help with the direct assessment of fire?

That's a tough one Ira, because human physiology plays such a role in the events and colors seen. Pupil dilation determines whether/how much points of dispersed light are clipped as they recombine... Two people may see different events and colored elements in the same diamond & environment, depending on what's happening physiologically.

So where we can talk with a degree of consistency about light lost vs returned, angular spectrum, pattern & contrast in a diamond we're currently confined to talking about dispersion (and scintillation) in terms of "potential." This is where some experts are divided: Direct assessment gives an actual number in limited scenarios - ray tracing via computer modeling arrives at predictions for multiple models. It's a great and exciting area of research.

My personal opinion is that we're moving towards a day where modeling will become harmonized for use in both cut design and, at some level, future standardization of assessment.

Date: 5/27/2009 8:05:40 AM
Author: Ellen
John, as usual, very well written information. Succinct, and in laymens terms for ease of understanding. The pics really are worth a thousand words.. Thank you for taking the time to do this. I see it fast becoming a reference point for those of us trying to help future shoppers.

You sir, are the true definition of a gentleman and a scholar.

(ok, minus all that hair)

Please dearest, refer to it as Excellent polish.

I'd like to address some of the other comments here but am late for a meeting. LLL (does anyone else still use this?)

 

[Regular Guy]

Date: 5/29/2009 12:39:26 PM
Author: John Pollard

Date: 5/27/2009 7:51:23 AM
Author: Regular Guy
John, I asked this over there, where it earlier came up, but I am thinking of it here, so will ask it again, and maybe you (or any of your friends) would like to share?

Are there workable tools, do you think, to help with the direct assessment of fire?

That''s a tough one Ira, because human physiology plays such a role in the events and colors seen. Pupil dilation determines whether/how much points of dispersed light are clipped as they recombine... Two people may see different events and colored elements in the same diamond & environment, depending on what''s happening physiologically.

So where we can talk with a degree of consistency about light lost vs returned, angular spectrum, pattern & contrast in a diamond we''re currently confined to talking about dispersion (and scintillation) in terms of ''potential.'' This is where some experts are divided: Direct assessment gives an actual number in limited scenarios - ray tracing via computer modeling arrives at predictions for multiple models. It''s a great and exciting area of research.

My personal opinion is that we''re moving towards a day where modeling will become harmonized for use in both cut design and, at some level, future standardization of assessment.

I wonder if two different things need to be teased out?

a) whether the characteristic of fire is particular to the interaction with the individual, which I think you are saying, and where this is less an inherent native characteristic of a diamond

b) or...to the extent it may be an identifiable characteristic, associated with some properties (as for example, as is frequently recognized here, described by Garry, that, for example, a smaller table will typically be more associated with fire...all things being equal)...that it may be more difficult to capture with by way of a device to measure this directly, rather than indirectly....which I think Serg is saying?

There may be 4 things here, but you get the idea.

Thanks for reviewing...

 

[gwendolyn]

What a fantastic article, John! The information is educational and precise without being full of confusing jargon, and the photographs perfectly highlight the range of possible looks in rounds. Plus, you worked in a drum reference! You get an A+.