The price forecasting at the end of the article prices lab paper by it’s weight in diamonds. Now, that’s a deal, no ? Not to mention that cut is entirely made not born like carat, color and clarity presumably are.
At a first read, a couple of its from the article proved particularly useful to navigate the tangle. Here they are, starting with an eye opening question:
Paul also notes that trade observers are educated in a certain way of looking, judging and thinking. No matter how ‘blind’ you make their observations by not giving them any parameters before judging, they can identify certain parameters and they may inevitably be influenced in their observational judgements. "
OK, in for a penny, in for a pound.
Since I have no proper reputation to sully, here I go. Thanks in advance for forgiving big mistakes. I find the Pricescope info hangs together logically in a way that I feel like usually, with one thing pointing in a straight line to another, one idea flows pretty well to the next, and I am motivated to participate. In the case of this response…I’m more going out on a limb.
In the case of this study you''ve reacted to, Garry, no, I''ve not read the original. Hard enough time skimming yours. Still, some reactions, and questions, I''ll try to re-state here.
Regarding my last point above, and generally...your review is very "context dependent" upon the original piece. So, it is a review...naturally. You say right at the beginning: "(the categories) may not be the basis of the final grades. It seems their foundation is incomplete which means that this analysis of it must also be incomplete." Relatedly, on your screen 10, where you present the chart of reported effects to light performance, you introduce it with this comment: "The GIA study noted during the observational survey that factors other than proportions played a role in diamond beauty. This table attempts to simplify those observations." My hunch is simply that your intention in providing the details of the chart is to shoot down the paper tiger and intended suggestion that proportion data is not substantially sufficient to provide for cut grades. The items in the chart do not seem substantive, and I was betting you were just trying to draw the items out, putting them in black & white. Wrong?
My point on your comments on pricing and cut were just that...good stuff. I recall reading similar or identical comments on this board before, presume they were for you, and bear repeating.
Finally...a "second" reaction to your piece, and the first point I tried to make above...really, this point is embedded in some fundamental questions I have about HCA and diamond cut grading generally. First of all, allow my complete relative ignorance about crown & pavilion angle actual patterning in the real world. Of course, without this knowledge, setting up schemes to measure them could be sharply criticized. And yet, let''s point out that your fundamental typology of BIC, TIC and FIC as describing the spectrum of ideal cuts has as one of them a class (FIC) that you describe as occurring as about 1 in 2000, wasn''t it? So...basic questions:
1) Given the classic graphical display represented coincident with the HCA report, where you get the big red pathway going from “Northwest to Southeast,” i.e., upper left to lower right, I suppose that your frequent cry to suggest the range of ideal cuts can be expanded is consistent with this broader big red valley…given this broad swath of red…why the more narrow option for AGS0 in their newer system…why not a bigger spectrum. Also, and likewise…to what extent does that big red area map onto your own system of categorizing of 0 – 2…maybe the match is not that great.
Date: 1/12/2005 2:45:52 AM
Author: lostdog
Re Paul from Antwerps comments about the trade observers being "preconditioned"
While I think I know what you are getting at, that the stones were being judged relative to the exisiting concept of ideal, but on some level changing the preconceptions of those involved in the study with the results of the same study sounds a bit circular in logic from the outset.
That said, that some people with ''trade eyes'' might be looking at a stone for isolated characterisitics and biasing the grading response without really looking at the visual performance seems to be an important failing. Is there a breakout in the study of consumer preferences compared to professionals?
There''s still a lurking question of who the beholder of the beauty is, i.e. judging beauty presupposes some standard.
Here is a link to one of my most ardent hate club fan leaders discovery of a diamond that in their opinion proved that the numbers are a bad predictor of diamond beauty. Now I agree that such a stone would, by its numbers, look very attractive - but the trade observers would easily have picked it as "wierd". http://www.diamondtalk.com/forums/showthread.php?t=54913
I still wonder that symmetry isn''t properly accounted for, as you point out. Yes - it is a problem that GIAmis aware of, but solving such a problem when you have 50 years of baggage is not so easy. As Einstein said "You can not solve problems with the same thinking that created it". GIA have made attempts to bring people from outside the organisation and the industry to work on this project - but even that is not easy to pull off.
From page 12:
''For instance diamonds that have painted or built up upper girdle facets like EightStar diamonds® were said to show “little...''
An honest question, do EightStars have painted facets? Yes, of course they do
- - -
Cat 5 does appear there only make sure that Cat 4 is better than something.
- - -
Maybe this belongs in a separate topic, but what would be the ultimate ultimate methodology and grading system?
scan the diamond and build an excellent 3D model, then use physics and software to judge the diamonds beauty based on a range of basic light responses calibrated by humans. The greater benefit of such a system is that it can then be used to reverse engineer the design of truly beautiful diamonds - it can even lead to freestyle designs and one off pieces that follow the outline of the rough diamone yet still produse a beautiful diamond. Sergey Sivovolenko who designed DiamCalc and the worlds most advanced Sarin type scanners is the world leader in this field.
Date: 1/12/2005 3:10:26 AM
Author: Regular Guy
In the case of this study you''ve reacted to, Garry, no, I''ve not read the original. Hard enough time skimming yours. Still, some reactions, and questions, I''ll try to re-state here.
Ira you are an excellent contributor. I asked who had read the article because I want to know that people are not only responding to my biased view of the world.
Perry you said you had read the article - did you mean mine, or th GIA''s - that is what i meant
''The GIA study noted during the observational survey that factors other than proportions played a role in diamond beauty. This table attempts to simplify those observations.'' My hunch is simply that your intention in providing the details of the chart is to shoot down the paper tiger and intended suggestion that proportion data is not substantially sufficient to provide for cut grades. The items in the chart do not seem substantive, and I was betting you were just trying to draw the items out, putting them in black & white. Wrong? Wrong - if you read over many of my posts in the past few months you will find references where I quote those opinions because by and large i agree with them (aside from the issue that they have a fallable symmetry grading system).
My point on your comments on pricing and cut were just that...good stuff. I recall reading similar or identical comments on this board before, presume they were for you, and bear repeating. Yes but Paul told me not to put them in because it is purely my opinion and it is not a "review" of the GIA paper. he is right of course (he is a very wise person) but i could not resist because i am a weak fool
Finally...a ''second'' reaction to your piece, and the first point I tried to make above...really, this point is embedded in some fundamental questions I have about HCA and diamond cut grading generally. First of all, allow my complete relative ignorance about crown & pavilion angle actual patterning in the real world. Of course, without this knowledge, setting up schemes to measure them could be sharply criticized. And yet, let''s point out that your fundamental typology of BIC, TIC and FIC as describing the spectrum of ideal cuts has as one of them a class (FIC) that you describe as occurring as about 1 in 2000, wasn''t it? So...basic questions:
1) Given the classic graphical display represented coincident with the HCA report, where you get the big red pathway going from “Northwest to Southeast,” i.e., upper left to lower right, I suppose that your frequent cry to suggest the range of ideal cuts can be expanded is consistent with this broader big red valley…given this broad swath of red…why the more narrow option for AGS0 in their newer system…why not a bigger spectrum. Also, and likewise…to what extent does that big red area map onto your own system of categorizing of 0 – 2…maybe the match is not that great.
Firstly, the big red area is less than 2 on HCA. Secondly if diamond cutters were not pealised in the market by that vicious "crown angle greater than 36 degrees" then they would cut more of those stones - there is plenty of that type of rough and the yeild is great. thirdly AGS have a 10 inch viewing distance which I think is madness - Peter agrees that diamonds that look great at 14 inches make fabulous pendant and earring stones. Not everyone can or wants to examine the beauty of a diamond from 10 inches.
2) Generally, if we allow that the big red area on the HCA presentation suggests good performance…and I do know that upper left portions and lower right portions do stake out the BIC and FIC typology…then it would seem a mistake to have poorer cut diamonds follow the track of this big red area, which is what at least GIA 1 – 3 seems to do. So, maybe this doesn’t make any sense…and I’ll qualify it by pointing out that in the last month, people on the Pricescope board have queried about diamonds that are very clearly in the outlying blue areas of the chart at the upper right, suggesting some actual diamonds under consideration do exist out there…but my question is basically…wouldn’t it make more sense for poorer cut diamonds to follow a path perpendicular to the big red area on the HCA chart..or does this make no sense…perhaps representing no, or not many actual diamonds. I’m intending to attach below a highly primitive mockup of us just such a chart. And that’s my 2 cents for today. Your indulgence is greatly appreciated. I do not completely follow this last bit - but i think your questions may be answered?
Thank you for the reply
I see... honestly, I didn't get to split the HCA scores.
DF, with a grading system already in the mix it''s not that simple.Date: 1/11/2005 7:456 PM
Author: Dancing Fire
GIA should forget about putting a cut grade on their cert ,just put all the specs and let the consumer decide by using their eyes,HCA,AGA,IS,B-scope,Isee2 etc,etc...
Ana, I was intrigued by this as well. The hair-splitting I''ve done regarding minor facets is mostly relative to stones with a tight set of major proportions (already is a known performer), though I have interest in unilateral applications. Rhino and I were on the verge of starting a discourse on this very topic when we both went on vacation for a week.Date: 1/12/2005 72:22 AM
Author: valeria101
(3) Minor facets... well, I have no reason to disagree that at some point this added cut grading factor is splitting a very, very thin hair (the starin of H&A ideals that is). But, is it possible to improve the looks of a stone with so-so crown&pavilion match by modifying the minors ? Jonatahan''s page does not deal with this of course. It seemes that GIA does. Wrong ?
300x240.png)
