Grading systems and 'gaming' them: An eternal story?

[John P]

When I first joined PS, there was an emphasis on educating consumers about top tier diamonds and the workmanship, science and artistic vision that went into cutting these stones. We had webinars and education was encouraged.

I sure do miss those. In addition to allowing professionals from different sectors to present in their fields-of-specialty without fear of seeming promotional, it permitted all-important shared conversations with the other participants. They made it possible to interact in a more immediate and human way. Often those webinars covered far more than the title advertised.

 

[John P]

My own feeling is that the assessment of beauty remains personal and may be greatly assisted by the use of measurements, tools and technology, but cannot be done without human perception which varies in every person, just like fingerprints. We can guide consumers in selecting diamonds that should be durable, good visually for their weight, symmetric, well polished, attractive in outline, eye-clean, not eye clean, colorless, tinted or fancy color, etc, etc...But we should not put the final selection, one that ought to be based on beauty at the mercy of any system of arbitrary grading. It just won't work. What I do see at present is that a consumer can buy primarily round and princess cut diamonds with a good deal of security sight unseen due to the advancement of diamond cut grading. To a lesser exrtent we see this going forward with other shapes that have enough volume of sales for the market to see comparative ASET and other pertinent images. This is an ongoing and evolving process and not a matured one. It is changing all the time and the "gaming" of the system actually may serve to fine tune the outcomes over time.

I like the overall perspective Dave. I'm not sure about the final sentence, as I think that GIA's EX grade first encouraged an overall bump-up in global cut-quality by necessity (!) But as more manufacturers learn to target outer limits with slightly more financial success...or far more success in a 5m carat per yr production...it's natural that levels of optimization will suffer and creativity is further killed.

Neil's reset is sobering. "Victory" is indeed the money game in the big picture. Maybe that's not criminal since we're not curing cancer here, but I'd like to believe that systems will continue to evolve as technology does. Not simply to illuminate basic performance differences - in that way that systems like GIA's AGSL's and PS do - but also to assist with taste and cut-perception (see my VR fantasy on the last page).

 

[John P]

Saying people can only buy diamonds in a b&m is not an acceptable answer and that your company happens to have b&m's all over the country raises a huge conflict of interest when you post this.
That a supplier/his employees and his dealers with b&m's all over the country is leading attacks on internet shopping is a huge problem because it is self serving and biased.

I never said people can only buy in B&Ms. And I never attacked internet shopping.

But to say inferior stones are being a: sold by dealers here b: recommended by consumers c: that you cant chose a diamond you will love sight unseen is wrong.
Add in your and Paul's positions and it starts sounding very self serving.

Again, I never said those things.

Karl, you may be chasing ghosts in my posts because I work for Paul's company (?) In any event I have not seen you respond to the meat of my input ( here, here, here and here. In the interest of being clear, here are my contributions:

1. Human cognition is uniquely individual. One person may prefer diamond "A" in person to diamond "B" when the two have the same paper statistics. Any jeweler operating a fair showroom can attest to this. Can we discuss?

2. Some people "see" things in terms of the Cs which not everyone is able to detect; sometimes subtly, sometimes overtly, not unlike wine-tasting. Can we account for this in some way through technology? Or is perception uniquely individual?

3. Anyone who has read Ray Kurzweil's The Age of Spiritual Machines may agree we are in the mid-fourth epoch, technologically, in terms of diamond cut assessment. What will come in the future will far surpass what we now enjoy, at a rate of exponential growth.

4. What will happen when future advancements in technology fine-tune the minimum-level of what to buy, or provides more choices involving creativity and new cuts and even taste factors? Can we discuss?

I had the opportunity to work for a wonderful online seller, with great success. Now I work for a supplier and have the opportunity to function in three very different theaters: Online-only, brick-and-click and showroom-only. Each theater, or market if you prefer, has different pros and cons. My discussions with really smart pros (colleagues, competitors and friends) lately involve the awareness these markets have about each-other. As we advance in technology, and more B&M jewelers realize there is life beyond the fax machine ---sorry guys I could not resist--- the abilities and limitations of current systems (whether lab or online) will logically be debated, as will the emergence of improved systems. It would be nice to discuss them here.

 

[John P]

My biggest problem on here is when people are told to go look at diamonds to see what they like, because I DID that personally and most of us simply do not have access to a well cut selection locally to really have a meaningful experience. Not to mention color cannot be discerned in almost any jewelry store due to the lighting. More power to those who have access to go somewhere that does, but most of us do not. Tiffany was the best overall selection I could find, and guess what? All the diamonds looked fantastic in their lighting even though I am sure few, if any, were superideal!

Paul, my apologies if this is totally off topic. I just wanted to explain my own experiences which shape why I recommend what I recommend. I still am not sure where I fall in comparison to the other posters on this thread! I wasn't posting as much in 2010 due to a move and other big family events and apparently missed the big shift in posting. I think maybe slg is coming from the same place?

DS, I don't think it's off-topic at all. And maybe I see the cup more half-full, but I really value the advice consumers often give here to "go look." Selection and ability to make comparisons are surely limited in many places, which I wager is the cup half-empty part? Tiffany & Company is a stellar place to see consistently superior cut quality, but they don't often let you take the diamond into various rooms, outside, etc. The armed guards kind of deter that...

I'm not sure where you live now, but what is the situation in your local bling-venues? Do you find any that educate using either proportions or (thin chance) ASET? Many malls have "H&A" type diamonds but they're often pretty mass-produced and not always consistently in what the AGSL or PS-favored bullseye for that make tends to be. I'm not saying that's bad on its face, but have seen examples that would never pass muster here.

What I have been pleasantly surprised to see is better quality in more commercial areas than in the past. I am not talking about quality that will satisfy the most enthusiastic technophiles, but better cuts accessible to the common man. What still lacks, however, is user-friendly perspective for shoppers in live situations who would like to know what level of quality they are really seeing... No jewelry store on the planet is about to greet you with "Good afternoon and welcome to Second-Best-Bridal. Steep-deeps over there. Fancies with no cut grade in that counter, and our soft-cert special today is F color offered at H pricing!"

 

[Rockdiamond]

Great points John!

DS- with regards to Tiffany's- if we're going to use an example of "non tech selection" they are a very good operation to use.
I would venture to guess that all the round diamonds you saw were very well cut.
Maybe not the same as your preferred "super ideal" cuts but it's probably fair to call them "different", as opposed to inferior.
I have been involved in selling to Tiffany's - many years back- but even then, their standards were extraordinarily tight. They did select amazing stones back then.
We can probably use them as an extension of my points to Garry earlier about how may super well cut stones can be selected sans ASET/HCA/BS/IS

I have to admit, curiosity got the better of me, and I've been in Tiffany's 57th street flagship store. Yes, the showcase lighting is .....well, designed to make their stuff look great- but there were big windows and I did have a chance to look at the pieces outside the bright spotlights. OK, I had to slug a guard or two ( kidding!!!)


I'd also like to point to Tiffany's as an example of how the "gaming" to achieve maximum yield and GIA EX at the same time affects buyers.
I can attest to the fact that more and more cutters are going for what seems to be the same set of proportions lately- by that benchmark, "gaming" certainly does seem to exist. As John rightly points out- this does seem to indicate that many more people will be getting a better cut stone than in years past- albeit with a more "Tolkowski-like" personality.
But the rounds I looked at in Tiffany seemed more like the 60/60's I prefer. Not that I could ask to see GIA reports on them- it's not that kind of shopping experience- but they did seem less "ideal" and more "open table" scintillation type cuts.

My point is that specialty stores can avoid the "cookie cutter" small table stones- including those that might be categorized as "steep deep". Wholesale buyers might have to look harder- but they can find different proportion sets out there. Paul's amazing work is a great example.
BTW, pursuant to Serg's comments, we're still looking for an example of what a "steep deep" is, and what it lost when a stone falls into this category.

 

[Venice]

When I first joined PS, there was an emphasis on educating consumers about top tier diamonds and the workmanship, science and artistic vision that went into cutting these stones. We had webinars and education was encouraged.

I sure do miss those. In addition to allowing professionals from different sectors to present in their fields-of-specialty without fear of seeming promotional, it permitted all-important shared conversations with the other participants. They made it possible to interact in a more immediate and human way. Often those webinars covered far more than the title advertised.

That's what I came to PS for, and it's what I miss the most, too.

 

[Serg]

When I first joined PS, there was an emphasis on educating consumers about top tier diamonds and the workmanship, science and artistic vision that went into cutting these stones. We had webinars and education was encouraged.

I sure do miss those. In addition to allowing professionals from different sectors to present in their fields-of-specialty without fear of seeming promotional, it permitted all-important shared conversations with the other participants. They made it possible to interact in a more immediate and human way. Often those webinars covered far more than the title advertised.

That's what I came to PS for, and it's what I miss the most, too.

Yes, it was very interesting time.
Unfortunately PS does not give enough benefits more for independent experts to spend time here.
that is interesting in first time, become very boring after many times reiterations.
PS does not create new knowledges more.( At least I do not see it, but may be I missed something because I am very rare on PS last years)

 

[diagem]

When we start talking about Princess Cuts and other fancies it takes the discussion to a while different level.

And I believe this is where energy should go towards...
We must also differentiate between Square symmetrical Princess Cuts and other asymmetrical Fancy shaped Diamonds...
To start with...., Fancy cuts can enjoy a wide variety of C&P angle combinations vs the tight 34.50-40.80 combinations standard Round Brilliants require.
Minor facets are becoming key when designing new cuts, may I dare to say even more important than the mains in some designs.
I believe I read it in Bruce Harding's Antwerp paper (can't find the link but its here on PS somewhere) where he mentions the lack of R&D in the 'anti-thesis' angle combination area's.

I have been playing around for some time already with these anti-thesis combinations and am finding myself fascinated with some of the results.

Just returning from a nice weekend of Texas sun and fun.

Yoram, here is Bruce's Antwerp presentation:

https://www.pricescope.com/journal/study-colored-stone-diamond-cutting-angles

I did not recall the correlation you make but I am sure you're correct. Also relevant; Bruce summarizes the similarities (but not sameness) of established systems by saying: "...historic preferences are due to human perception. No measurement by instruments or statistical manipulation of data will provide this insight." This returns us to cut-perception and cognition factors outside of our ability to assess in current metrics.

In the spirit of sensory advances and 3D graphics technology I wonder if the future of VR will allow people to wear a visor to see a projection of a distant object as-it-would actually in their hands...and to what level of resolution this could take place. Michael Deering posed an abstract on 3D graphics around a decade ago which claimed 10,000,000,000 triangles per-second to be necessary to saturate the human visual system.

http://www.michaelfrankdeering.com/Projects/EyeModel/limits.pdf

<< A model of the perception limits of the human visual system is presented, resulting in an estimate of approximately 15 million variable resolution pixels per eye. Assuming a 60 Hz stereo display with a depth complexity of 6, we make the prediction that a rendering rate of approximately ten billion triangles per second is sufficient to saturate the human visual system. >>

Thanks for the link..., just noticed it was all along above my head...

You are going to make me work hard just to understand your writing. But here are my thoughts:

My main points from Bruce's article in relation to Diamond cuts (mainly fancy cuts) are:

"...HISTORY and the VIEWER
Stones of different RI must be cut with different facet slopes for best appearance. Diamond cutters don’t realize this because they work with only one material, whose RI is 2.42. Colored stone RI’s vary from 1.5 to 2.3.

"...SIMILARITIES
The four charts below have special interest. In each case the historic ‘best’ combination (black dot) is on the upper edge of the shaded diagonal zone which represents bezel-to-table rays with the viewer seeing himself. Such an obvious similarity must have a reason; none was found until Garry Holloway, of Australia, suggested one in 2000: the viewer sees himself in the pavilion main facets but not in the breaks ('halves' to diamond cutters) – thus seeing contrast of light and dark between these facets and on-off light and darkness of these facets as the stone, light source, or viewer moves.

It is agreed that contrast is more noticeable to the eye and makes a stone appear more brilliant. The dynamic on-off contrast due to motion is also eye-catching and is commonly called ‘scintillation’.

Thus the historic preferences are due to human perception. No measurement by instruments or statistical manipulation of data will provide this insight.

Why not more than one combination of pavilion and bezel facet slopes along this boundary? Indeed such combinations provide good-looking stones; this has been confirmed by subsequent extensive 3D studies by computers, the results of which are shown in the next segment."

Possibilities might be endless if only cutters dare to explore outside the box.
Problem is..., the material is becoming too scarce and expensive discouraging cutters from further exploring and sticking to the standard shapes, cuts and facet designs.

Different and novice scintillation effects may be waiting to be discovered on the other side of the "norm" boundaries as shown in the "faceting limits charts" for Diamonds in Bruce Harding's Antwerp Paper linked above.

I have been toying around with some odd P/C angle combinations and am liking some results I am getting to....

 

[Garry H (Cut Nut)]

My main points from Bruce's article in relation to Diamond cuts (mainly fancy cuts) are:

"...HISTORY and the VIEWER
Stones of different RI must be cut with different facet slopes for best appearance. Diamond cutters don’t realize this because they work with only one material, whose RI is 2.42. Colored stone RI’s vary from 1.5 to 2.3.

"...SIMILARITIES
The four charts below have special interest. In each case the historic ‘best’ combination (black dot) is on the upper edge of the shaded diagonal zone which represents bezel-to-table rays with the viewer seeing himself. Such an obvious similarity must have a reason; none was found until Garry Holloway, of Australia, suggested one in 2000: the viewer sees himself in the pavilion main facets but not in the breaks ('halves' to diamond cutters) – thus seeing contrast of light and dark between these facets and on-off light and darkness of these facets as the stone, light source, or viewer moves.

It is agreed that contrast is more noticeable to the eye and makes a stone appear more brilliant. The dynamic on-off contrast due to motion is also eye-catching and is commonly called ‘scintillation’.

Thus the historic preferences are due to human perception. No measurement by instruments or statistical manipulation of data will provide this insight.

Why not more than one combination of pavilion and bezel facet slopes along this boundary? Indeed such combinations provide good-looking stones; this has been confirmed by subsequent extensive 3D studies by computers, the results of which are shown in the next segment."

Possibilities might be endless if only cutters dare to explore outside the box.
Problem is..., the material is becoming too scarce and expensive discouraging cutters from further exploring and sticking to the standard shapes, cuts and facet designs.

Different and novice scintillation effects may be waiting to be discovered on the other side of the "norm" boundaries as shown in the "faceting limits charts" for Diamonds in Bruce Harding's Antwerp Paper linked above.

I have been toying around with some odd P/C angle combinations and am liking some results I am getting to....

Me too Yoram.....the trouble I am having with a totally new potential design is that I have too much brightness!!!

 

[Rockdiamond]

When we start talking about Princess Cuts and other fancies it takes the discussion to a while different level.

And I believe this is where energy should go towards...
We must also differentiate between Square symmetrical Princess Cuts and other asymmetrical Fancy shaped Diamonds...
To start with...., Fancy cuts can enjoy a wide variety of C&P angle combinations vs the tight 34.50-40.80 combinations standard Round Brilliants require.
Minor facets are becoming key when designing new cuts, may I dare to say even more important than the mains in some designs.
I believe I read it in Bruce Harding's Antwerp paper (can't find the link but its here on PS somewhere) where he mentions the lack of R&D in the 'anti-thesis' angle combination area's.

I have been playing around for some time already with these anti-thesis combinations and am finding myself fascinated with some of the results.

Just returning from a nice weekend of Texas sun and fun.

Yoram, here is Bruce's Antwerp presentation:

https://www.pricescope.com/journal/study-colored-stone-diamond-cutting-angles

I did not recall the correlation you make but I am sure you're correct. Also relevant; Bruce summarizes the similarities (but not sameness) of established systems by saying: "...historic preferences are due to human perception. No measurement by instruments or statistical manipulation of data will provide this insight." This returns us to cut-perception and cognition factors outside of our ability to assess in current metrics.

In the spirit of sensory advances and 3D graphics technology I wonder if the future of VR will allow people to wear a visor to see a projection of a distant object as-it-would actually in their hands...and to what level of resolution this could take place. Michael Deering posed an abstract on 3D graphics around a decade ago which claimed 10,000,000,000 triangles per-second to be necessary to saturate the human visual system.

http://www.michaelfrankdeering.com/Projects/EyeModel/limits.pdf

<< A model of the perception limits of the human visual system is presented, resulting in an estimate of approximately 15 million variable resolution pixels per eye. Assuming a 60 Hz stereo display with a depth complexity of 6, we make the prediction that a rendering rate of approximately ten billion triangles per second is sufficient to saturate the human visual system. >>

Thanks for the link..., just noticed it was all along above my head...

You are going to make me work hard just to understand your writing. But here are my thoughts:

My main points from Bruce's article in relation to Diamond cuts (mainly fancy cuts) are:

"...HISTORY and the VIEWER
Stones of different RI must be cut with different facet slopes for best appearance. Diamond cutters don’t realize this because they work with only one material, whose RI is 2.42. Colored stone RI’s vary from 1.5 to 2.3.

"...SIMILARITIES
The four charts below have special interest. In each case the historic ‘best’ combination (black dot) is on the upper edge of the shaded diagonal zone which represents bezel-to-table rays with the viewer seeing himself. Such an obvious similarity must have a reason; none was found until Garry Holloway, of Australia, suggested one in 2000: the viewer sees himself in the pavilion main facets but not in the breaks ('halves' to diamond cutters) – thus seeing contrast of light and dark between these facets and on-off light and darkness of these facets as the stone, light source, or viewer moves.

It is agreed that contrast is more noticeable to the eye and makes a stone appear more brilliant. The dynamic on-off contrast due to motion is also eye-catching and is commonly called ‘scintillation’.

Thus the historic preferences are due to human perception. No measurement by instruments or statistical manipulation of data will provide this insight.

Why not more than one combination of pavilion and bezel facet slopes along this boundary? Indeed such combinations provide good-looking stones; this has been confirmed by subsequent extensive 3D studies by computers, the results of which are shown in the next segment."

Possibilities might be endless if only cutters dare to explore outside the box.
Problem is..., the material is becoming too scarce and expensive discouraging cutters from further exploring and sticking to the standard shapes, cuts and facet designs.

Different and novice scintillation effects may be waiting to be discovered on the other side of the "norm" boundaries as shown in the "faceting limits charts" for Diamonds in Bruce Harding's Antwerp Paper linked above.

I have been toying around with some odd P/C angle combinations and am liking some results I am getting to....

Great post Yoram.
This conversation provides a unique framework if for no other reason that different cutters are participating.
Between you and Paul- it's almost like you're at opposite ends of the spectrum.
Both are committed to cutting to perfection, that being a definite goal in mind.
It may cost more rough, but in the end of the day, people are willing to pay extra for such perfection
The difference is that Paul knows what the result is supposed to look like. He does an established design, to the max.
One carat or 10 carat- same design
Yoram is , to me, a great example of a cutter who uses the rough differently in that the ultimate design is far more fluid- there's so many more choices.
In a sense this wold be an argument against any cut grade- in that it totally discourages creativity.
Surely that's why cut grades for fancies are far more controversial- and not accepted by the trade at large.
Not saying the trade does not respect fine makes- and value it higher- but with fancy shapes, the determination of whether or not to pay more for fine make is done primarily by human examination. Other than PS participating tradespeople, ASET is rarely used. We're talking some of the biggest names in the world- famous for make - and selecting fancies pretty much solely by loupe and eye.
This might make it easier to "game the make" but also possible for others to innovate without the need to fit into an arbitrary ( somewhat) set of parameters.

 

[Karl_K]

1. Human cognition is uniquely individual. One person may prefer diamond "A" in person to diamond "B" when the two have the same paper statistics. Any jeweler operating a fair showroom can attest to this. Can we discuss?

John I going to take your points one by one and respond.

Go out and see which one you like falls on its face because the lighting and environment is artificiality created most usually to showcase diamonds.
In my opinion and observation someone can not truly judge the diamond they bought until they have lived with it in their world/environment/lighting for a few days.
This is why return periods are so important both b&m and internet and is also one reason many b&m's refuse to offer refunds.
One can rig the lighting to showcase any particular diamond type and then train the viewer to look for what one wants them to see.
That has little to no bearing on how it will appear in the daily life of the person.

 

[Karl_K]

2. Some people "see" things in terms of the Cs which not everyone is able to detect; sometimes subtly, sometimes overtly, not unlike wine-tasting. Can we account for this in some way through technology? Or is perception uniquely individual?

If a person has a preference to a certain look they can use technology to find diamonds with a simular look.

 

[Karl_K]

3. Anyone who has read Ray Kurzweil's The Age of Spiritual Machines may agree we are in the mid-fourth epoch, technologically, in terms of diamond cut assessment. What will come in the future will far surpass what we now enjoy, at a rate of exponential growth.

Not having read the book I am not sure what this has to do with anything? explain?

 

[Karl_K]

4. What will happen when future advancements in technology fine-tune the minimum-level of what to buy, or provides more choices involving creativity and new cuts and even taste factors? Can we discuss?

If they truly love the diamond, carefully shopped then viewed it in a lot of lighting conditions they have a stone they love.
No matter what diamond ones buy it may go out of style, they may like a different shape better, or DSS may set in.
A good exchange policy is a blessing in these cases.

 

[Karl_K]

1. Human cognition is uniquely individual. One person may prefer diamond "A" in person to diamond "B" when the two have the same paper statistics. Any jeweler operating a fair showroom can attest to this. Can we discuss?

John I going to take your points one by one and respond.

Go out and see which one you like falls on its face because the lighting and environment is artificiality created most usually to showcase diamonds.
In my opinion and observation someone can not truly judge the diamond they bought until they have lived with it in their world/environment/lighting for a few days.
This is why return periods are so important both b&m and internet and is also one reason many b&m's refuse to offer refunds.
One can rig the lighting to showcase any particular diamond type and then train the viewer to look for what one wants them to see.
That has little to no bearing on how it will appear in the daily life of the person.

I wanted to expand on this a little.
As mentioned earlier in this thread I have always said that one should observe a new diamond in as many lighting conditions and locations as possible within the return period.
Different lighting shows different aspect of a diamonds performance and how it reacts in your environment is the most important thing to you.
I believe that some diamond professionals while they have good intentions are so used to looking a diamonds under the ideal conditions they created that they lose perspective on what a costumer actually sees once they get it out in their life.
It would be interesting to redo the GIA study with consumers and sending them home with 2 diamonds at a time mounted side by side and have them report back after 3 days which was better to them.
The results could be vastly different than what they got in a box using industry people.
I predict the results would shift dramatically around the edges and maybe even the middle would shift somewhat.

 

[oldminer]

Karl; No doubt you are totally correct about how different lighting will change the outcome of comparison between stones. For that exact reason every scientific study to create diamond cut or diamond light performance grading comes with a defined lighting environment which is called the "normal" lighting environment for that grading strategy. This "normal" lighting is not normal, everday lighting, but specifically constructed to create a repeatable and sufficiently bright environment in which to take readings or make comparisons with consistent results. It may not duplicate any natural lighting scenario but I believe most of the systems are using a "normal" lighting that is more like a retail store environment with an observer viewing the diamond with overhead spotlighting partially obscured by the observer's head. This use of "normal" lighting is a sound practice and one could never use a natural lighting scenario, or multiple scenarios because there would be no consistency of results. No system can work without consistent, meaningful results. Also, no system will be accepted for diamonds if the results are far more confusing than the topic deserves or more confusing than anyone without a PHD can understand.
xxxx
We can subjectively judge the end result of diamond cutting like we judge the quality of art or crafts. We can objectively measure and grade performance, and a set of limited physical parameters to see where certain styles of craftsmanship and certain levels of performance safely coincide due to the very consistent optical and physical nature of diamond. Where the failing is of such a combined system is that it leaves out some very beautiful potential cut styles for diamonds by making them grade lower than they would grade if judged by performance alone and then by craftsmanship alone. Some people would love unusual, or less common cut styles which looked excellent and which may have been crafted in some less common or less standardized way.

 

[Paul-Antwerp]

Paul,
Perhaps it would be better if you define what is meant by minimum level of a top grade, since you state it as a fact but we have no definition what you mean by minimum level of a top grade.

Are you talking about performance, like cutters cutting to a minimum level of "scintiallation" required by the top grade?

Are you talking about cutting near the physical boundaries between two top grades?

Whatmeworry,

I took the time today to go through this thread from start to finish again, and I noticed that I omitted to answer your very pertinent question. My apologies. I am under time-pressure today, but will organize to allow time for this tomorrow.

Live long,

 

[whatmeworry]

Paul,
Perhaps it would be better if you define what is meant by minimum level of a top grade, since you state it as a fact but we have no definition what you mean by minimum level of a top grade.

Are you talking about performance, like cutters cutting to a minimum level of "scintiallation" required by the top grade?

Are you talking about cutting near the physical boundaries between two top grades?

Whatmeworry,

I took the time today to go through this thread from start to finish again, and I noticed that I omitted to answer your very pertinent question. My apologies. I am under time-pressure today, but will organize to allow time for this tomorrow.

Live long,

Paul,
I re-read your first statement and you defined minimum for GIA as weight retention and minimum for AGS as non-H&A but looking forward to more clarification from you.

 

[diagem]

My main points from Bruce's article in relation to Diamond cuts (mainly fancy cuts) are:

"...HISTORY and the VIEWER
Stones of different RI must be cut with different facet slopes for best appearance. Diamond cutters don’t realize this because they work with only one material, whose RI is 2.42. Colored stone RI’s vary from 1.5 to 2.3.

"...SIMILARITIES
The four charts below have special interest. In each case the historic ‘best’ combination (black dot) is on the upper edge of the shaded diagonal zone which represents bezel-to-table rays with the viewer seeing himself. Such an obvious similarity must have a reason; none was found until Garry Holloway, of Australia, suggested one in 2000: the viewer sees himself in the pavilion main facets but not in the breaks ('halves' to diamond cutters) – thus seeing contrast of light and dark between these facets and on-off light and darkness of these facets as the stone, light source, or viewer moves.

It is agreed that contrast is more noticeable to the eye and makes a stone appear more brilliant. The dynamic on-off contrast due to motion is also eye-catching and is commonly called ‘scintillation’.

Thus the historic preferences are due to human perception. No measurement by instruments or statistical manipulation of data will provide this insight.

Why not more than one combination of pavilion and bezel facet slopes along this boundary? Indeed such combinations provide good-looking stones; this has been confirmed by subsequent extensive 3D studies by computers, the results of which are shown in the next segment."

Possibilities might be endless if only cutters dare to explore outside the box.
Problem is..., the material is becoming too scarce and expensive discouraging cutters from further exploring and sticking to the standard shapes, cuts and facet designs.

Different and novice scintillation effects may be waiting to be discovered on the other side of the "norm" boundaries as shown in the "faceting limits charts" for Diamonds in Bruce Harding's Antwerp Paper linked above.

I have been toying around with some odd P/C angle combinations and am liking some results I am getting to....

Me too Yoram.....the trouble I am having with a totally new potential design is that I have too much brightness!!!

You should be able to control contrast with the some pavilion facets.

 

[Karl_K]

Karl; No doubt you are totally correct about how different lighting will change the outcome of comparison between stones. For that exact reason every scientific study to create diamond cut or diamond light performance grading comes with a defined lighting environment which is called the "normal" lighting environment for that grading strategy. This "normal" lighting is not normal, everday lighting, but specifically constructed to create a repeatable and sufficiently bright environment in which to take readings or make comparisons with consistent results. It may not duplicate any natural lighting scenario but I believe most of the systems are using a "normal" lighting that is more like a retail store environment with an observer viewing the diamond with overhead spotlighting partially obscured by the observer's head. This use of "normal" lighting is a sound practice and one could never use a natural lighting scenario, or multiple scenarios because there would be no consistency of results. No system can work without consistent, meaningful results. Also, no system will be accepted for diamonds if the results are far more confusing than the topic deserves or more confusing than anyone without a PHD can understand.
xxxx
We can subjectively judge the end result of diamond cutting like we judge the quality of art or crafts. We can objectively measure and grade performance, and a set of limited physical parameters to see where certain styles of craftsmanship and certain levels of performance safely coincide due to the very consistent optical and physical nature of diamond. Where the failing is of such a combined system is that it leaves out some very beautiful potential cut styles for diamonds by making them grade lower than they would grade if judged by performance alone and then by craftsmanship alone. Some people would love unusual, or less common cut styles which looked excellent and which may have been crafted in some less common or less standardized way.

Dave,
This topic would take an entire thread on itself so im not going to go in depth.
I dont disagree that much with what you wrote but there is no "normal" lighting, it varies person to person what types and intensity of lighting they are in day to day.
Consistent results that are not relative to that person is not all that helpful.

 

[Rockdiamond]

Karl; No doubt you are totally correct about how different lighting will change the outcome of comparison between stones. For that exact reason every scientific study to create diamond cut or diamond light performance grading comes with a defined lighting environment which is called the "normal" lighting environment for that grading strategy. This "normal" lighting is not normal, everday lighting, but specifically constructed to create a repeatable and sufficiently bright environment in which to take readings or make comparisons with consistent results. It may not duplicate any natural lighting scenario but I believe most of the systems are using a "normal" lighting that is more like a retail store environment with an observer viewing the diamond with overhead spotlighting partially obscured by the observer's head. This use of "normal" lighting is a sound practice and one could never use a natural lighting scenario, or multiple scenarios because there would be no consistency of results. No system can work without consistent, meaningful results. Also, no system will be accepted for diamonds if the results are far more confusing than the topic deserves or more confusing than anyone without a PHD can understand.
xxxx
We can subjectively judge the end result of diamond cutting like we judge the quality of art or crafts. We can objectively measure and grade performance, and a set of limited physical parameters to see where certain styles of craftsmanship and certain levels of performance safely coincide due to the very consistent optical and physical nature of diamond. Where the failing is of such a combined system is that it leaves out some very beautiful potential cut styles for diamonds by making them grade lower than they would grade if judged by performance alone and then by craftsmanship alone. Some people would love unusual, or less common cut styles which looked excellent and which may have been crafted in some less common or less standardized way.

David- how would you say "performance" is objectively measured?

I agree with Karl on this point- there is no "normal" lighting. This is part of my argument of why any light performance standards can't possibly cover all the possibilities.
But I do ask in earnest- what means are you suggesting to measure and grade light performance?

 

[Paul-Antwerp]

Paul,
Perhaps it would be better if you define what is meant by minimum level of a top grade, since you state it as a fact but we have no definition what you mean by minimum level of a top grade.

Are you talking about performance, like cutters cutting to a minimum level of "scintiallation" required by the top grade?

Are you talking about cutting near the physical boundaries between two top grades?

Whatmeworry,

Again, my apologies for the late reply. I will try to be as detailed as possible.

There are various grading-systems, one more complicated than the other. Let us first look at a cut-grading-system no longer in existance, the old (pre-2005) AGS-system. The cut-grade was based on average proportions independently, so if the average pavilion angle was between certain limits and the average crown angle was and the average table-size (to name three), the stone would qualify for AGS-0 in proportions. As a result, with the AGS-report relatively popular, we saw the supply of AGS-0-diamonds concentrating around the area with the deepest allowable average pavilion and the steepest allowable average crown, a combination that is actually the origin of the term steep/deep. I must add, the fact that this happened was probably a combination of some people intentionally aiming for this and others unintentionally delivering this.

Unfortunately , at the end of the 1990’s, a certain Garry Holloway (kudos to him) stood up with a theory about an inverse relationship between crown and pavilion angle and that the steep-deep-combination actually was a less performing area within the AGS-Ideal-grade. That and his subsequent introduction of the Ideal-scope met with a lot of resistance, particularly on the then popular forum DiamondTalk, and it was part of the reason why he, and later many others (including myself) were banned from that forum.

Compared to the old AGS-system, the current GIA-cut-grade is slightly more sophisticated, very much in line with the HCA-system. Still, this system works with average angles, that are even rounded to some extent, but the inverse relationship between crown and pavilion angles is taken into account. Somebody looking for the minimum-level in this system would thus make sure that:
- The average angles are a certain number,
- That that average angle will be rounded towards a number within a certain grade,
- They use a combination of crown and pavilion that retains the highest weight.
In practice, this still leads to examples of steep/deeps, although the most prominent examples in the old AGS-system are probably not possible anymore within the GIA-EX-grade.

A next step is the current AGS-system, which works with actual angles, not averaged. The system is a bit more of a black box, because of its complicated nature compared to the simplified GIA-system, and AGS overcomes that by distributing grading-software. In such a system, the search for the minimum-levels is a bit more complicated, but it still hinges on finding the angle-combinations giving the highest weight-retention. Other than that, we must consider what the system actually grades and what it neglects. The basis of the AGS-system, just like the GIA-system and most other tools, is an assessment of brightness only. Potential fire is a minority-part of the AGS-grade, but it is not based upon the latest fire-studies of the lab, and basically only handles the extent of fire that goes together with brightness. The assessment of scintillation is totally absent in the AGS-grade.
This eventually leads to a variety of levels of scintillation and fire within the top AGS-grade, and depending on your way of thinking, you can classify this as a difference in performance or a difference in taste. And the simple logic of game-theory, as Neil explained in this thread, is that the automatic concentration will end up at the minimum-level.

Looking at PS as a grading-system is a bit tricky, since there are no established rules. The advice on PS depends on the person offering the advice, on his or her preferences and on his or her sophistication in assessing the online-information. In comparison with the AGS-system, it can be discussed which of the systems is the most sophisticated (strict), but the similarity is that like the AGS-system, it is based on the assessment of brightness mainly, and not on the assessment of scintillation. Furthermore, with no established rules, it evolves over time, one could say that its strictness is a curve over time, with bottoms of low strictness and peaks of higher strictness.
At the bottom of the curve, I would say that the minimum-level of PS is the following:
- For rounds, a HCA-score below a certain number (evolving from 2 to 2.5 and sometimes lower) and a ‘decent’ ideal-scope, with the definition of what is decent also in evolution.
- For fancy-shapes, it goes down to the level where the vendor being capable of offering an ASET-picture is sufficient for a thumbs-up.
It can be debated whether this actually is the minimum-level of the PS-system, but it is clear that it would need to be a lot better to be more strict than the current AGS-system, for which I have just described that the system does not cover the complete ‘performance’ or ‘taste’ of the diamond.

I hope that this somewhat answers your question.

Live long,

 

[Garry H (Cut Nut)]

Paul,
Perhaps it would be better if you define what is meant by minimum level of a top grade, since you state it as a fact but we have no definition what you mean by minimum level of a top grade.

Are you talking about performance, like cutters cutting to a minimum level of "scintiallation" required by the top grade?

Are you talking about cutting near the physical boundaries between two top grades?

Whatmeworry,

Again, my apologies for the late reply. I will try to be as detailed as possible.

There are various grading-systems, one more complicated than the other. Let us first look at a cut-grading-system no longer in existance, the old (pre-2005) AGS-system. The cut-grade was based on average proportions independently, so if the average pavilion angle was between certain limits and the average crown angle was and the average table-size (to name three), the stone would qualify for AGS-0 in proportions. As a result, with the AGS-report relatively popular, we saw the supply of AGS-0-diamonds concentrating around the area with the deepest allowable average pavilion and the steepest allowable average crown, a combination that is actually the origin of the term steep/deep. I must add, the fact that this happened was probably a combination of some people intentionally aiming for this and others unintentionally delivering this.

Unfortunately , at the end of the 1990’s, a certain Garry Holloway (kudos to him) stood up with a theory about an inverse relationship between crown and pavilion angle and that the steep-deep-combination actually was a less performing area within the AGS-Ideal-grade. That and his subsequent introduction of the Ideal-scope met with a lot of resistance, particularly on the then popular forum DiamondTalk, and it was part of the reason why he, and later many others (including myself) were banned from that forum.

Compared to the old AGS-system, the current GIA-cut-grade is slightly more sophisticated, very much in line with the HCA-system. Still, this system works with average angles, that are even rounded to some extent, but the inverse relationship between crown and pavilion angles is taken into account. Somebody looking for the minimum-level in this system would thus make sure that:
- The average angles are a certain number,
- That that average angle will be rounded towards a number within a certain grade,
- They use a combination of crown and pavilion that retains the highest weight.
In practice, this still leads to examples of steep/deeps, although the most prominent examples in the old AGS-system are probably not possible anymore within the GIA-EX-grade. Infact the GIA system goes well past the worst AGS 0 on the old parametric system. For a 57% table size a 41.2 pavilion angle and a 36.5 degree crown angle can be GIA Ex. AGS Gold (another long story) would set 34 degrees as a maximum crown angle for a 41.2 pav. Or a 36 degree max crown angle with a 40.6 or 40.4 pav angle. All for 57% table sizes. You can see it all here http://www.octonus.ru/oct/mss/gia-agspgs.phtml

A next step is the current AGS-system, which works with actual angles, not averaged. The system is a bit more of a black box, because of its complicated nature compared to the simplified GIA-system, and AGS overcomes that by distributing grading-software. In such a system, the search for the minimum-levels is a bit more complicated, but it still hinges on finding the angle-combinations giving the highest weight-retention. Other than that, we must consider what the system actually grades and what it neglects. The basis of the AGS-system, just like the GIA-system and most other tools, is an assessment of brightness only. Potential fire is a minority-part of the AGS-grade, but it is not based upon the latest fire-studies of the lab, and basically only handles the extent of fire that goes together with brightness. The assessment of scintillation is totally absent in the AGS-grade.
This eventually leads to a variety of levels of scintillation and fire within the top AGS-grade, and depending on your way of thinking, you can classify this as a difference in performance or a difference in taste. And the simple logic of game-theory, as Neil explained in this thread, is that the automatic concentration will end up at the minimum-level.

Looking at PS as a grading-system is a bit tricky, since there are no established rules. The advice on PS depends on the person offering the advice, on his or her preferences and on his or her sophistication in assessing the online-information. In comparison with the AGS-system, it can be discussed which of the systems is the most sophisticated (strict), but the similarity is that like the AGS-system, it is based on the assessment of brightness mainly, and not on the assessment of scintillation. Furthermore, with no established rules, it evolves over time, one could say that its strictness is a curve over time, with bottoms of low strictness and peaks of higher strictness.
At the bottom of the curve, I would say that the minimum-level of PS is the following:
- For rounds, a HCA-score below a certain number (evolving from 2 to 2.5 and sometimes lower) and a ‘decent’ ideal-scope, with the definition of what is decent also in evolution.
- For fancy-shapes, it goes down to the level where the vendor being capable of offering an ASET-picture is sufficient for a thumbs-up.
It can be debated whether this actually is the minimum-level of the PS-system, but it is clear that it would need to be a lot better to be more strict than the current AGS-system, for which I have just described that the system does not cover the complete ‘performance’ or ‘taste’ of the diamond.

I hope that this somewhat answers your question.

Live long,

A nice poted history Paul.
See my comment in blue above

 

[Allison D.]

I've been struggling for a few days in how to consolidate my thoughts on this down to simple bites.

With respect to 'gaming the system' and countering the natural evolution, I'm guessing it could be a non-issue if there is good balance in the range betwen high and low within the grade. The range between top and bottom of a grade should be narrow enough to prevent significant variances, but wide enough not to require an absolute value to hit. (Example might be "A" students......90 to 100 would be too wide a range, but 99-100 might be unreasonably restrictive. 97-100 might be the right balance between uppper/lower ends of A student).

Continual refinement of grading systems would help as well, provided the refinement doesn't make it all but impossible to achieve to grade.

PS isn't really akin to a grading system to me. Grading systems in their purest form measure against standards without considering impact on the consumer. Lab issued grading reports are merely professional, disinterested (presumably) opinions of experts that set the benchmark for establishing market value. They don't care if the customer has to pay more (or less) for a stone as a result of their opinion; they issue the grade without consideration for that. While it may provide some assurance to a less-confident shopper that his diamond 'performs well' or is of a nice make, I feel it's primary function is to help set fair market value.

PS is considerably different because the community's 'recommendations' are influenced by the impact on the customer, especially when it comes to the fifth C - cost. If everyone had unlimited funds, it would be great to sit here and extoll the virtues of Kobe beef, but when not all budgets will support Kobe beef, something's gotta give, right? Beyond that, there are some people who just don't GET the masses fawning over Kobe beef because they truly do prefer a nice cheeseburger.

Since there is no way to 'legislate' or standardize preferences that will universally apply to all, it's hard to consider PS a 'grading system'. There may be times when people do indeed say "good enough", but that's often based on sensitivity to the poster's OWN stated values and priorities, and it's really not the place of the community to tell him why he should prefer something else.

To me, PS is more of a virtual neighborhood where people can solicit opinions. It makes sense that if I were to poll the 8 neighbors on my street about who their preferred landscaping providers are, their recommendations would be influenced by their buying values (cost, time to complete the job, variety of plants, professionally dressed employees, etc.) and who they happened to use. If I ask for their opinions, I do recognize their responses may weight things that aren't important to me and I'd adjust the weight of those recommendations to me accordingly. I also realize their experiences are limited to those they've used and may not include other great providers.

Likewise, there are several folks on PS who prefer better clarities, better colors, and better makes, but that may not be important in the values of the poster asking.

PS mission statement wasn't to cultivate cut-nuts, though that certainly was a predictable side effect of the learning curve. It's was to create a place where people could get meaningful data to inform their buying choices, not to tell that the only right buying choice is the one Skippy would choose (apologies to Skippy for being the example study this time). In fact, most times, PSers explain *why* they each prefer something, and that will help an inquirer determine if that's a valid reason for him, too.

With all that, I don't think there is a "gaming" of recommended parameters here. If anything, transience of regular posters influences recommendations more than most other things. There are scores of posters who used to post heavily here who don't anymore, so the current visitors' input can only include those folks who take the time to offer input here now. Unless there is a way to increase the base of participants, I don't see how to meaningfully impact the suggestions.

 

[Serg]

Whatmeworry,

before 2005 AGS cut grading system used rectangular zones( see red rectangulars here http://www.gemology.ru/cut/english/podrobno_2.htm)

corner this biggest pavilion and crown gave definition for Steep-Deep diamonds. See for example P41.2P35.8 for Old AGS0 and P41.9Cr38.8 for old AGS2

but current AGS and GIA cut grading systems have not rectangular zones and they do not include such corners and P41.2P35.8 is out of range modern AGSO and GIA Ex.

in same time GIA EX is wider than AGS0 and P41.2P35.8 is close to GIA EX zone.

if we consider modern AGS0 we can see what for fixed Crown angle and table 57, the pavilion angle has range only 0.4-0.6 degree.

for my understanding such zone can not have any steep-deep diamonds in Principal ! modern AGS0 diamond can not be steep and deep in same time, because this corner had been deleted from AGS0.

Same had been done for GIA Ex, steep-deep corner had been cut. Though GIA Ex is wider than ASG0 in two times( for example for T57 Cr 35.5) pavilion range is 1.2 degree instead 0.6 degree for AGS0, I do not see Old ( according old definition ) Steep-deep diamonds in GIA Ex.

I never saw new definition for steep-deep diamonds for AGS0 and GIA Ex.

Also I never saw Infinity cut grading system ( rules for selection diamonds according Infinity cut quality and brand). I asked to publish such rules ( system ) on PS early.

 

[Karl_K]

Looking at PS as a grading-system is a bit tricky, since there are no established rules.

Actually there are rules they are just passed on by example.
They are:
Without images your shooting in the dark is the first.
2nd is that lab grades is just the beginning AGS0/GIA ex is only a starting point.
The crown/pavilion relationship is considered including HCA + Shallow pavilion with obstruction issues is considered.

The the images are looked over for:
optical symmetry
leakage
obstruction
painting/digging
med. long or short lgf% (this is an assessment of potential scintillation characteristics)
lgf% relationship to the c/p angle (on the extremes, not needed that often)
anything out of the ordinary
effects of inclusions
if h&a is claimed the hearts are examined on the image they demand.
.........
If someone has their heart set on dealing with a vendor that does not provide all the information then they are helped the best that can be done with limited information.

I can name 10 maybe more pro-sumers capable of running that list and dozens of others who can do parts of it.
Often one will tackle one part and another a different part that they are comfortable with.

 

[Karl_K]

PS mission statement wasn't to cultivate cut-nuts, though that certainly was a predictable side effect of the learning curve. It's was to create a place where people could get meaningful data to inform their buying choices, not to tell that the only right buying choice is the one Skippy would choose (apologies to Skippy for being the example study this time). In fact, most times, PSers explain *why* they each prefer something, and that will help an inquirer determine if that's a valid reason for him, too.

That is the part of the picture but there have always been cut-nuts around and many people have worked very hard to make sure there are well informed and diamond cut educated consumers here to help others.
That we are seeing far fewer fan favorite based recommendations is a very good thing.

 

[John P]

1. Human cognition is uniquely individual. One person may prefer diamond "A" in person to diamond "B" when the two have the same paper statistics. Any jeweler operating a fair showroom can attest to this. Can we discuss?

John I going to take your points one by one and respond.

Go out and see which one you like falls on its face because the lighting and environment is artificiality created most usually to showcase diamonds.
In my opinion and observation someone can not truly judge the diamond they bought until they have lived with it in their world/environment/lighting for a few days.
This is why return periods are so important both b&m and internet and is also one reason many b&m's refuse to offer refunds.
One can rig the lighting to showcase any particular diamond type and then train the viewer to look for what one wants them to see.
That has little to no bearing on how it will appear in the daily life of the person.

Karl, thanks for the comments. My travel schedule is resulting in gaps in my reply-times. Sorry about that.

First of all, I share your opinion about living-with the diamond as key to embracing it. This is the logical conclusion of my long-standing blind-date comparison. To that end my advice to shoppers has always been to insist on return/refund policies; whether live or online. I cannot agree that live viewing ever "falls in its face" though. In fact one of the oldest PS axioms regards the superiority of live viewing. "The eyes have it."

Unless one lives in a cave I suspect we have all seen diamonds. Some people may not really care to get into the Cs of it all beyond "I need this thing at this time due to some crazy tradition that says I need it." I'll leave them aside for the moment.

For people interested in chasing "appeal" factors, whether to an average degree or to the ends of the earth like some of us, the advantage to seeing diamonds live is the ability for that individual to determine macro-and-micro differences in taste and perception. The macro typically involves everyone (Do I prefer round? Do I prefer 57-facet round? Do I prefer 60/60?) and the micro involves many (Do I prefer strong or weak contrast patterns? Do I prefer more white or more colored flashes? Do I prefer larger-broader or smaller-faster flares? Do I prefer disorganized or structured scintillation? Do I prefer A to B for whatever reason?). Determining macro-elements doesn't necessarily require side-by-side comparisons but determining micro-elements does for most people.

As an example that is well-documented here: For years I was involved in comparisons of normally-indexed versus crown-painted “superideal” diamonds of equal-beauty (based on history Karl may argue that one style is less-desirable but I will not). The candidate diamonds would be shown to consumers side-by-side under fluorescent office lights, under softer/indirect light, then under natural light (large window) and finally under a “portable jewelry store” I provided for the office; this was a desk-mounted set of bright LED spots which made the diamonds exlpode, as-if in a spotlighted showroom. In many cases the diamonds impressed viewers equally; they could see differences but had no preference. In other situations viewers had some kind of preference between the two styles. In nearly all cases, once the differences were explained (done only at the end of the session; one of the most valuable lessons I learned from Brian G.) the viewers nearly all claimed to be able to see the cut differences...whether they all could or not is up for speculation. But what's important is that in all cases the viewers concluded by identifying a specific diamond as their favorite. Even more relevant is that this also happened when the candidate diamonds were of a single flavor (painted or not). While considered equal in beauty according to grades, images and reputation human cognition still made a choice. That choice was not always the one predicted but it was always personal.

Over all this is the umbrella of perception: Some people “see” more than others and that ability (or inability) will guides some decisions and make others moot. But I cannot say what any person will see/perceive or what any person will prefer.

Ergo, my advice to those buying online has always been to take the diamond on a "world tour" of favorite places to make comparisons (understanding some jewelers may permit outside diamonds and others may not). I even know people who ordered two, three or four candidates - some are avid Pricescopers - and “lived” with them for a few days to choose, but that process may not be practical for all.

For those wishing to take such a "tour" and make comparisons, a point DiamondSeeker touched-on is relevant: Comparing at a certain level depends on finding B&M stores with cut-quality examples worthy of being included in such a comparison. Tiffany, Jared and HOF dealers are commonly mentioned here, yet these places (a) may not be accessible to all (b) may not welcome comparisons and (c) may not present a variety of different lighting conditions.

It's a given that in jewelry showrooms one can expect lighting to be arranged to maximize appearance. This is logical, just as in car-dealers’ showrooms, fashion shows, etc. It is critical to overcome the single-environment for comparisons. In my own travels I've consulted with showrooms to create a "diamond-walk," where clients can take a tray or temporary settings with candidates and walk through a span of different illumination scenarios: Multiple direct spotlighting (normal in most showrooms), an indirectly lighted area (darkened or beneath a counter), diffused lighting (like a classroom or office) and natural lighting (near a window or -better- outdoors). These are some of the staples. In some cases the jewelers have needed to create space and adjust lighting to do this, which has taken some convincing at times. Pleasantly, the payoff has been gratitude from clients for creating a unique process seen as fair and educational. I urge all sellers to try it. I also urge them to encourage return-trips for such comparisons, during both the sales process and the return period.

 

[oldminer]

David- how would you say "performance" is objectively measured?

I agree with Karl on this point- there is no "normal" lighting. This is part of my argument of why any light performance standards can't possibly cover all the possibilities.
But I do ask in earnest- what means are you suggesting to measure and grade light performance?

I am using the words "Normal Lighting" in the scientific way, not in the regular terminology of daily speech. Normal lighting in science means a specifically chosen, arbitrary lighting scheme which the scientist has decided to use in the measurement of some optical or physical feature of an object. This lighting should have relevance to some common, regular model of lighting when possible, and must be highly repeatable in all aspects. Lighting created with the use of calibrated LED's of known color temperature, distribution and voltage will help make a chosen lighting scheme repeatable and consistent. If such a scheme provides the right environment for meaningful collection of data and the scientist uses it on a regular basis, then that lighting scheme is said to be "Normal Lighting". I hope my statements now make a bit more sense. There are limitless lighting schemes in regular daily life.

In my 13+ years working along with the team at ImaGem, Inc, I have been exposed to digital devices which analyze the amount and character of light from known sources in their "normal lighting" scenario. These devices are based primarily on analysis of very high definition images. When one knows the exact amount of light being projected on a diamond, one can measure with great accuracy and repeatability certain characteristics of the light coming back to the observer's eye which in digital image making is the sensor in the digital camera's sensor. How much light comes back, how much potential scintillation there is, how well defined a pattern and contrast is being shown in the image. By sub-pixel analysis, these "facts" can be "measured". When these numeric, repeatable results are combined with studies of human preference, we have data which strong correlates to how pretty a diamond will look to the majority of observers. Even if the beauty analysis is imperfect in that not every observer is the same, the data is rather perfect and clearly defines performance. A higher amount of performance does not always equate to "better", but for those interested in interpretation of what numerical results mean, getting solid data on a repeatable and consistent basis is very meaningful. If a diamond were to be made with too much light return and not sufficient contrast, it would lack an element required for beauty even though the measure of light return was very high. A diamond with high sparkle and overall lower light return might well appeal to some folks, but in terms of measured performance it would be somewhat lower in light return. It is a balancing act to create a beautiful diamond and not a contest of who can make every measured aspect higher and higher at the same time. Such a diamond won't look so good to most of us.

 

[John P]

2. Some people "see" things in terms of the Cs which not everyone is able to detect; sometimes subtly, sometimes overtly, not unlike wine-tasting. Can we account for this in some way through technology? Or is perception uniquely individual?

If a person has a preference to a certain look they can use technology to find diamonds with a simular look.

To a good degree. But the full science isn't there yet, Karl.

3. Anyone who has read Ray Kurzweil's The Age of Spiritual Machines may agree we are in the mid-fourth epoch, technologically, in terms of diamond cut assessment. What will come in the future will far surpass what we now enjoy, at a rate of exponential growth.

Not having read the book I am not sure what this has to do with anything? explain?

It applies to the above: In 2000 only a flawed parametric system existed. BrillianceScope was the most "advanced" technology in-use on the popular diamond forum of the day. No HCA. No Ideal-Scope. No ASET (these things were in R&D). Yet the population of that forum had as much confidence in their system as we do in today's far-more-sophisticated PS system. In ten years there has been advancement, but I still cannot click a mouse and share with you (or anyone) an object in the way your senses will perceive it in real life. By 2020, given the exponential growth of technology in this epoch, perhaps that will be possible (?) reference my Michael Deering abstract. Maybe not. But the ability to make decisive recommendations will unarguably be farther-along and superior to what we have now.