Mapping the beauty of a diamond: The components and their relationships

[Regular Guy]

When I took business stats quite ago, I tried to make some wild eyed guesses about things, submitted it to my prof, and I never heard back. This may be like that. But...sorry guys...tracking the discussion for some time now, my mind is going here, and if anyone is interested in going here with me...I'd appreciate the help.

Initially, I'm just going for the lay of the land:

Requested: Feedback, of any kind you might like.

Observed: Gentlemen in some aspects of the trade have been the most vocal about variances from category I (i.e., Jonathans from GOG & WF, Garry, Paul...for example). Also, observed, not a lot of banter from our appraisers on these variances, no?

Target: 100% (In other words, if a future cut grade will be arrived at...it will have one single result...whether it's the new AGS0, or whatever, and so somehow, despite the fact that there are these many components that go into the beauty of a diamond, somehow, they'll need to be factored together into one whole result. Obviously, there are subtleties, and for Chess masters, computers may not do, and you just see the whole board. But...from the point of view of creating an expert system...you'll want to assess weights to the elements...as much as you can. So, your indulgence in tweaking this will make me delighted!).

I Relationship between crown & pavillion - 70%
a) taken as a whole, somehow, pavillion against crown has greater weight...70% to 30%? But is 100% of this imbalance due to the additional factor of the table size?
II a - Table size: 4.5%
b - Culet .5%
III - Facet construction - 10% (my bad...last night, I looked at the terms more closely presented in the tutorial here, and got a beginning glossary for a lot of the terms being used here, i.e., lower girdle facets, star, etc.
a) presume this includes yaw effects (another butchered concept...regrets in advance).
IV - girdle effects...whether cheated, gouged, etc. 10%
V - gases...non-iterated additional elements, without consideration to how inclusions will effect the beauty 5%

Once again, sorry. I'm a regular guy, and reading the board only this morning had me put in a 5% adjustment for the table. If this is actually spelled out better (I did a poor man's tour of teaching sites, including GOG, Nice Ice, and here before writing, but it was quick, my stamina is not what it used to be, and directing me back to another source that pulls this together may be what I need), let me know.

Thanks in advance for your indulgence,

 

[valeria101]

There could be different components to weigh, and not necesarily diamond dimensions...

I was surpised by the descriptions on the (new) DB website. They explain "quality" is a different thing than "beauty" and list half a dozen optic effects (and nothing else! - just optics) to analyze "beauty". Not unlike GIA's cut study goes.

Well, 'can't say I don' t like the approach.

For once, those crown&pav angles give rules applicable to one cut diagram only. Wider numeric rules may not be precise enough once smething as narrow as AGS0 or H&A set the target for way finer than visual observation. So looking at the effects of the cut directly for criteria that are both visual and applicable to any shape sounds better to me.

It would take me a deep breath to figure out if such criteria can be weighed into one metric or something else would work better. This, just because visual effects are obviously "additive": they show all at once only and cannot be taken apart in real life even though that can be done for analysis sake. The cnstruction of the index effectively decides how much trade off is possible (or desirable) between any two metrics... and a few other things.

 

[Regular Guy]

Ana,

It''s possible I don''t follow your train of thought. Just looked at the DeBeers site. Seems like what they''ve done is said...OK...

Quality...Beauty....I see you scratching your head to figure out how you get the beauty. Solution...stop scratching your head!

They might seem to suggest you can look at these two separate elements, without looking at how you might get one from the other. Fact is, when you just begin to step into their analysis of beauty...the latter two of their 5 items are described as: light return geometry and symmetry, and coincide with the language they use for cut, where they do reference angles & proportions.

 

[valeria101]

Date: 2/26/2005 8:21:59 AM
Author: Regular Guy


They might seem to suggest you can look at these two separate elements, without looking at how you might get one from the other.

Well, there''s no scratching: rather a reasonably clear message that important price factors (listed under "quality") might not be as critical for looks (="beauty") as ... well, cut is.

I would gladly let it to cuters to figre out how to make diamonds bright. Of course at some point it comes down to numbers. I am not sure I want to know what those numbers are as long as the result looks great. Once some numbers are pinned down, it just means (I would think) that tweacking cut details to achieve optic effects is uselessly bounded.

The logic seems simple: grade the effects of the cut, not some detail of the process (some numbers) under the assumption it is a sufficiently strong determinant of the output. That may be relevant for internal control, but that''s no longer a concern once the product is out there - I can''t say I want to know how the cuting process went: just want the result

Aside this... If fancy cuts are appealing, it would be fair to open some direct comparison among them. Like This

Keeping the story to grading characteristics mostly fit for rounds doesn''t help put things into perspective. ''Guess I am a dreamer. (remember that article by Wise: "A Cut Above" ? the link is gone...).

 

[valeria101]

Some indeces like that are lurking around PS already (see next post, attach failed here)...

Aside those below, the HCA does use some weighths (that Garry does'n tell

).
Both HCA and DiamCalc turn numbers into guess-timate optical effects (=stuff that should show).
Iscope, Bscope, Isee2 have their own weighted measures for some standardized direct observation. The AGA charts have their own rating and do not even pretend to guess optics or relate directly to some visual impression.

Among all these, it just remains the burden to choose. It is not at all clear to me that reading thourh all this stuff gets close to showing what one can look for inspecting diamonds in person. Shouldn't there be some relation ?

 

[valeria101]

 

[Regular Guy]

Ana,

A few thoughts:

Where you say:

I would gladly let it to cuters to figre out how to make diamonds bright. Of course at some point it comes down to numbers. I am not sure I want to know what those numbers are as long as the result looks great. Once some numbers are pinned down, it just means (I would think) that tweacking cut details to achieve optic effects is uselessly bounded.
The logic seems simple: grade the effects of the cut, not some detail of the process (some numbers) under the assumption it is a sufficiently strong determinant of the output. That may be relevant for internal control, but that''s no longer a concern once the product is out there - I can''t say I want to know how the cuting process went: just want the result

I take your point. Nevertheless, as the mind wanders, I think it naturally does wander towards cause & effect. Yes, utilities like the IS, potentially brilliancescope, and others designed to show the "effects" of a well cut diamond...perhaps these can stand on their own. Where gossip frequently goes here, of course, is to these other details, prompting -- at least in part -- me to write.

Also, you mention HCA''s weights...yielding output discussion the various aspects including scintillation, etc. Remember, the only input that gets you that output are those that go into the forumula to begin with...i.e., pavillion angle, crown angle, table, etc. What I''m trying to get at, in consideration of what Garry has provided some general nod to, and to acknowledge a great deal of discussion on other aspects of cut that go beyond significant crown & pavillion measurements...is how the pieces relatively fit together.

Finally, re your post of the charts...yes, this is helpful, thanks for the reminder...and even does try to get at that bigger final output, as you say, with cut only being inclusive of the total.

Perhaps a more comprehensive approach would be where this question is done in three pieces:

a) started here, seeing to what extent only the element of cut is componentially made up, with respect to it''s effects on beauty -- still trying to see how the parts make up the whole yielding 100%

b) take all 4Cs into account. Perhaps cuts makes 75%, yielding 25% to the effects of color, clarity, perhaps even size...seeking to get the components of man made vs organic yielding 100%

c) as you say...get a direct measurement...and then see to what extent what had been accounted for in (b), is able to account for the total output in (c). Maybe we''d find an accountable approach only predicts 50% of 100% of (c), and we''ll all just go out in a jeep and look for naturally occuring phenomena, and junk all the rest (doubt it).

Hey, btw, Ana, thanks for the interest...and what''s your time zone, anyway. How askew are you from eastern time?

 

[valeria101]

Time zone: I am eight hours "later" than Estaren Time. However, I need to coordinate with colleagues inthe Boston Area - so I''m quite used to the schedule.

About those numbers.... I am not sure how to start the story so I will jot down some thoughts as well.

It seems reasonable to consider the properties of each factor before decidng on a linear scale common to all (that is assumed by the constant weights).

About color
It is not obvious at all that each grade makes distinct visual impact. Assigning a weight to color would imply that. A really small weight would somehow acknowledge the week visual impact of higher grades but not work quite as well elsewhere. This is "normal" since the color grades are not set at equal "distances" from the start. Non-linear indexing is a pain...

About clarity
Well, this doesn''t really show until it becomes a "risk factor" (you know, looking at anything down to VS1 is safe bet, SI1 and below does not tell appearance acurately but warn that the respective item might pass or fail visual inspection). Same as above - a constant weight for "clarity" would imply that the difference between IF and VVS1 is as drastic as the difference between VS2 and SI1. Is it ?

About size
Well, don''t know what to say here. With the steep price increse with weight once shape, color and clarity are pinned down there isn''t any leeway for size. For a given budget there is room for size variation only if one of the other three parametets is relaxed. So it may work to just index those three.

About cut
I see what you mean about cause (numeric parameters) and effect (optic effects)... Can''t argue against of course. The difficulty seems to lie with establishing what is a detailed enough description of the "cause". The whole range of analysis is barely there: complicated things like the GemAdviser can take all the numbers in a cut diagram plus effective variances into account and spit out a photo-realistic model that can be precisely evaluated by numers alone (not necesarily in a unique manner or by a unique taste - but precisely by any such evaluation standard chosen). Since some evaluation of fire is under way ( as far as I know) - adding complexity to this model seems to have potential to approximate reality in a very convincing way. I am not convinced that a 3D "real media" software can''t produce better images than the GA, but thet''a another matter - don''t think those guys will volunteer to the diamond cut cause. At the other end... well, the HCA approximates diamonds with an unrealistic geometric shape (=taking the input numbers you have enough info to draw a cut cone for the crown and a cone for the pavilion) and makes educated assumptions about the rest. Those "educated assumptions" limit usage it seems (or are GIA and AGS with their new systems fools ?).
Ideally, there should be no significant difference between the grading based on visual observation, the light-measuring systems (B-scope, I scope) and the measurement based models (GA, HCA...). But that sounds like a loong and expensive shot. Each approach has it''s own laundry list of errors. It just seems to be a really long way to cover between cause and effect.

In all honesty, I am not a big fan of any of these approximations. Each demans a considerable leap of faith to accept some substitute for visual observation (which happens to be the use of the object in cause anyway). Somehow, it seems fair to keep this leap of faith as small as possible.

IMO, rating the "visual appearence" rather than some approximation of it''s cause reduces the leap of faith.
Not that increased sophistication of that "approximation" does not help. It does. Only between the current number-based and image-based cut grading systems the later seem to have covered more diastance arguably

.


... Anyway, I might never end digging into detail along these lines.

 

[Regular Guy]

Ana (and any interested others),

Appreciate your interest, of course. Based on what seems to me to be pretty extensive and high level discussions on these boards of recent on these topics -- going beyond getting just the right pitch of angles for pavilion & crown -- I think a better understanding of the relevance of this discussion has at least potentially significant implications for how anybody might choose to shop for an expensive item like a diamond...and likewise, this could have appropriate effects for gentle-people in the trade on this board as well -- as I'll try to say.

Ana, you've returned to your core point, and have done so for a good purpose (also, the good writer that you are, you do it well and concisely at your conclusion)...

IMO, rating the "visual appearance" rather than some approximation of it's cause reduces the leap of faith.
Not that increased sophistication of that "approximation" does not help. It does. Only between the current number-based and image-based cut grading systems the later seem to have covered more distance arguably.

I will agree with you. I agree with you, however, on both counts. Although it's logical to ultimately trust and go with an option you believe to be better because you are able to see this "betterness," -- and you can establish that you see this betterness either directly, with your eye, with a natural assist, like the IS, or with a more unnatural assist, like the Briliancescope -- what has been magnetizing to me, convincing to me, and influential enough to me thus far to help me "pull the trigger" with confidence has been the predictive systems...specifically...in my case, the HCA. However, note that this same predictive systems have existed with success and influence for quite some time, such that the AGS, and also, of course, AGA, draw from them as well.

I hope it will be background enough to say that in the times I have done diamond shopping with my eyes, confusion will typically arise as to which one I really like better, and as a result, despite Feydakin's frustration at seeing customers express a possible preference for one diamond, only to turn around and change their mind when they learn about either a better color or clarity seen elsewhere, and so I can understand completely the influence of this data. What I like to hear, of course, is Jonathan's description of how the Brilliancescope works, where he sees that it is typical that when his customers tend to like a diamond, the Brilliancesope likes it, too. The confound, here, is two-fold: bias not remedied without a blind-study, and dissonant opinion by other professionals who don't reach agreement on this tool's use, if only in principle. And personally, regarding the IS...I think in August there's a Gem show in the DC area, where I will have what I expect to be the gaul to bring it out and view diamonds with it. Meanwhile, and especially while not in a serious shopping mode, without experience using it, I feel at best ambivalent about it's use.

In the alternative, there is a convincing power in the idea of an HCA system...too much?...perhaps. (And that is what has been argued here, and is the cause for this discussion.) Because of the idea that the angles will predict light performance...I think Todd at Nice Ice purports a 98% predictive relationship...and in the case of the HCA in particular, the simplicity of looking for a yielded number of from 0 - 2, the system causes other list-serves to draw vehement attacks against this one, and post after post on this board asks about it.

The feeling with HCA is that you can really get your arms around it, right?

The question now, of course, becomes...well...even though the predictive systems like HCA and what HAS been AGS's system are easy enough to track, and be convinced by....relatively speaking...how sufficient is that data, after all?

In other words...although Garry will readily warn you that you should not rely too heavily on the HCA, since I find the alternatives wanting, to the extent that I will need to rely on the authority of a black box to provide me with a significant assist with my decision...choosing that black box will be important.

I've read recently here that based on AGS's evolution of processing of this information, only their future "black box" may be relied upon to take in the whole range of data that would be desirable to see. And, so, of course, maybe that's it...end of discussion. I can believe that really may be the case. Even so, though, what about for now, and until it is ready.

If you believe a lot goes into the elements of the beauty of a diamond, and you feel you can trust the evaluation of that only if your partner in crime (vendor, appraiser) has an understanding of those constituent parts...then you may be constrained to using only those vendors/appraisers with this understanding. Which...is why I'm asking this question.

A

Iterating the data and showing their relative relationships:

1) iterating the data

I tried a simple sort of the data at the beginning of this post, spelling out the possibly major defining elements. Not sure to what extent there is agreement on it. Whether the idea of optimizing beauty included only cut, or also, was inclusive of the other criteria that seem to have an effect on the experience of beauty...the question is reasonable. I guess GIA is including both. If AGS will only include cut (not sure) it may make the choice of source grading even more interesting. Also, however, it turns the question of how these various different elements get positioned with respect to weighting all the more important, as in (2) below.

2) The relationships between the data

The power of HCA, and the vigor on this board -- these are due to what many see here as the correct understanding as the relative importance of cut, overall, in the characteristics of a diamond. Understanding how this feature or fact can be mapped as data may help shoppers, more.

a) George Mason University has a program designed to help graduate students display data in a way, so that it is understood. Take a sine wave (is that what's it's called?), for example. Or, when your teacher in school says they are grading by the curve, the curve is the statistical presentation of data that is commonly used. A question: how to best present that. For example, we understand that in buying ideal cut diamonds, we are buying among the top 10% of those available. So, 10% on the curve is way out there. And the difference between one data point and another, as a percentage out of 100, is maybe small. But relatively, maybe the difference is big. So, although maybe crown & pavilion data make up even 90+% of what any consumer need to be concerned about, maybe the additional factors of optimizing on girdle and facet construction, are relatively minor factors in the total picture, still...attention to these details alone may push the diamond into the top 2% of performers, and a failure to understand these differences...being effectively insensitive to them...may not allow your vendor or appraiser to help you get there. Do you see what I'm getting at?

b) A book from awhile ago was called, I think, Ecotopia. It had, for the states, both California and especially NYC taking up a huge visual part of the territory intended to represent America. The intent to make visual those impacts that are considerable, which you wouldn't pick up if you just left it to a simple map to display, since NYC would otherwise be a speck, rather than something like 1/3 of the map. Of course, a more conventional way to do the same thing, when looking more narrowly at the end of the curve, is to make a box of just that data, and see how it performs when you blow it up.

c) then again, reading Garry's most recent posts, it sounds like potential technology and knowledge impacts may be making that end of the curve push much closer to the middle...that going to Kay's will allow you to pick up a beautiful diamond after all. Of course, he talks about it being brownish. So, here again...wouldn't it be interesting if we could use an arrangement of the relationships between data to help us value beauty, even in consideration of color...so we can know where to put our $$ with even greater precision?

B (oops, my family is up and I'm outta time)

Cutting to the chase...if this additional data matters, does my vendor understand it. If not, do I need to shop elsewhere.

C

Likewise, for the appraiser I choose.

Well, sorry to have abused you all. If the future...as has been suggested...is in AGS's hands, this may all be moot. In the alternative, there is now, people are buying now, having difficulty making graded choices with their own eyes, and these other data points and suggestions may make a difference. Just how much a difference, that will ultimately be up to the consumer. Understanding how this data all fits into the big picture could only help.

My 2 cents.