Light leakage, how can you tell in real life?

[Texas Leaguer]

HI Bryan,
Thank you for a thoughtful post.
It's been a while since some of these issues have been raised- and I will admit, I've learned a tremendous amount due to my participation over the years here.
Here's where I feel the interpretation of scientific data regarding reflector images, and Fancy Shaped Diamonds sometimes falls short.
In the case of the ASET chart Garry posted, it's quite clear which is considered better by whoever put the chart together.

My contention is that once a measurement is taken, you get a scientific result. Like a millimeter size, or a weight. That's an objective measurement. Once someone, or a a group of people categorize this objective result, it becomes a subjective result. Like a poll.
Who gets to say which of these scientific measurements are "excellent" as opposed to Very Good. The only method of truly describing them in a scientific manner is objective measurements.

When someone is deciding which type of light performance is "better" by virtue of a subjective label, like "excellent" or even "0" it is no longer merely a scientific measurement. It is an evaluation of a scientific measurement. Who gets to say where the line between 0 and 1 is on AGS scale?
Subjective.
IN fact, this could be a debate on the weight a lab should place on human observation at all.
Which goes to a real main point- beauty.
The fact is, not all experts in the field will agree that an AGS0 princess cut is a better cut than a slightly spreadier stone, which will show more green in an ASET, and fall short of 0 by AGSL standards.

We agree that there's a majority of poorly cut fancy shapes on the market- really nice ones are quite hard to find.
We agree that consumers need tools to assist them.

I'm suggesting the labels given on the chart above- from the page Garry posted represent a subjective opinion, giving us a higher possibility of misinterpretation opposed to a numerical value.

Here's an example of typical mis-read.
A truly well cut "crushed ice" Radiant cut will have a very "disorganized" ASET- and may indeed show leakage in the table. Yet the real life look of the diamond does not correlate the white areas in the ASET with anything negative at all.
On such stones large concentrations of red can be very problematic, in my opinion. The reason I say this is that in real life, the red areas on an otherwise nice crushed ice stone may appear dark.
Bryan, I would suggest this to you, as a highly regarded seller. If you have a client looking for a princes cut, and they are led to believe red is better- which is reasonable for people who read and post a lot to say, they may choose a stone with red for the wrong reasons, and be more likely to return.
I think its fair to say that any vendor participating in this forum regularly is dedicated to transparency for everyone's benefit
When we're assigning all these subjective titles to objective measurements, how much weight is placed on spread for the weight?


Here's a scientific fact.
Take a piece of rough, 10 carats. The weight and price of this rough are established, objective, scientific measurements.
The size, weight, and price of the resultant polished diamond is also an objective measurement.
What if the choice was a 7.5ct "Crushed Ice" stone- getting "Fair" ASET based on the chart above, or a 6ct stone which will get "Excellent" ASET ratings based on the chart above.
A well designed and cut "crushed ice" stone has a lot more light bounces. Such a stone shows a lot of green and some scattering of white. Not a lot of red in the well cut ones IMO. Such a stone can be very brilliant through a fairly wide range of viewing angles. The leakage identified in the ASET is compensated for when you move the diamond. We all agree large areas of leakage will cause windows that are generally undesirable in modern cut non specialty diamonds ( find me a non leaky horse head
However all diamonds will exhibit some leakage. In many cases leakage identified on ASET is not possible to see in real life.


So, for the same price a consumer can buy a well cut 11.5mm 7.5ct stone, or an AGSL0 cut grade 6.00ct stone, which will be noticeably smaller. The real world spread on weight a mm size might even be greater in many cases.
Hypothetical numbers, but real world truths.
I totally get the beauty of an AGSL0 fancy shape cut grade stone- and they are definitely worth the money for someone looking for that type of look.
The science that identifies larger brighter flashes with ASET is valid. Labeling it is the question.
And the science behind well cut crushed ice ( there- I've said it a few times already) is also remarkable, and can produce a stunning diamond.
When AGSL designates 0 cut grades for fancy shapes- how much weight is placed on spread?

David,
Thank you for taking the time to lay out your position. But again, I don't quite get the main point. You seem to be arguing against subjectivity, claiming that because established grading systems (including scientifically vetted ones) contain labels such as Excellent or Ideal, that they are somehow misleading.

Your comments, at the same time, contain multiple references to your own subjective judgments (labels). You talk about crushed ice with dominant green in aset that are "stunning", and about stones with ASET showing alot of leakage that you don't see in real life. And you reference tones with alot of red in aset that "look dark" to you. So you have your own standards and methodologies and you are entitled to your own value judgments and to communicate them with your own adjectives. So the answer to the question of who gets to assign the labels is obviously the entity creating the standard.

There is nothing misleading about it if you understand the underpinnings of whatever standard you are evaluating. For instance, GIA has a cut grading standard for rounds. Many people believe the top grade is too broad and they therefore seek more information to help select the truly excellent from those at the margins. Conversely, some people may find the AGS princess standard to be too strict and they see as perfectly acceptable diamonds that will not make the top grade in that standard.

You make a special point about spread and it certainly is important and it is definitely factored in to both the GIA and AGS systems. But spread alone will not get you a top grade from either lab. It is only one factor that is evaluated in relation to brightness, dispersion, leakage, contrast, and finish. In fact, the new tools available today, especially ray tracing technology, has finally opened our eyes to the fact that we can get so much more beauty out of a diamond by not cutting with an emphasis on the traditional goals of weight retention and/or spread.

And those tools and new ones yet to be developed offer the promise of taking us much further in our understanding. The work that Garry referred to regarding human perception, binocular rivalry and such, is kind of mind blowing.

So, on this basic premise I will agree with you: at some level of any diamond grading standard there are going to be decisions, value judgments, that can be construed to be 'subjective'. After all, the labs exist to help consumers understand the relative value of the diamond under consideration. Whether you find that standard useful may to some extent depend on whether you agree with the methodology of how those judgments were arrived at. On the other hand, you may find a system useful even if you think the labels put on it are not perfect, such as the example above of GIA Ex. This system is still used very effectively, by consumers who feel the label is too broad, as a filter to narrow down options to take a further look. And the same is even more true in the case of AGS Princess, since GIA reports are of little value in assessing light performance in this very popular shape.

 

[Serg]

A well designed and cut "crushed ice" stone has a lot more light bounces. Such a stone shows a lot of green and some scattering of white. Not a lot of red in the well cut ones IMO. Such a stone can be very brilliant through a fairly wide range of viewing angles. The leakage identified in the ASET is compensated for when you move the diamond. We all agree large areas of leakage will cause windows that are generally undesirable in modern cut non specialty diamonds ( find me a non leaky horse head
However all diamonds will exhibit some leakage. In many cases leakage identified on ASET is not possible to see in real life.

David,
1) Crushed Ice cuts have much less Fire than Good Cuts with big VF's.
2) Crushed Ice cuts looks much darker in Light Environment with black background then in typical LAB environment to check color and clarity.( where is a lot light from pavilion)/
Modern Crushed Ice cuts may compete and even Win in Brightness in compare with Cuts with Big Virtual Facets only in light environment with a lot of light from Pavilion.
In most Jeweller pieces Crushed Ice cut have much less Brightness .
Everybody may easy check it.

There is not technology to produce Crushed Ice cut without strong Leakage . ( may be it is possible design such cut but it is not possible to produce). But even if you may produce Crushed Ice without Leakage it has not Fire. It looks as many Melee diamonds.
If you need just Brightness then Buy Cluster of Melee diamonds.
7Ct well cut diamond has to have good balance between Fire, Brilliancy and Scintillation . 7ct Crushes Cut has not such balance.
what is reason to pay for additional 1.5ct and miss Fire?

Hi Serg- thank you for the response- thought provoking for sure.
Let me ask a simple question- a few actually.
1) Is it possible for the ASET to detect leakage which human eyes can not detect?
2) If so, should such leakage be considered a "problem"?


About the rest of what you wrote, yes we do disagree - specifically about the balance of Fire, brilliancy, scintillation AND spread.
I am working on an answer to the points you raised

1) Yes, ASET may show leakage which is not visible specially for Human with stereo vision . ASET image is not enough to grade even Brightness. I may proof it and give many examples.

most simple example is Ideal AGS 0 round diamond 6 mm and 2mm with exact same proportions.
ASET images are congruent; but Subjective Brightness, Brilliancy , Fire are different for these diamonds.

2mm round diamond has higher Subjective Brightness, 6mm round diamond has higher Fire

2) "Such " Leakage is not problem. But ASET may show the Leakage which is real problem for Human perception of diamond Beauty/

 

[Texas Leaguer]

HI Bryan,
Thank you for a thoughtful post.
It's been a while since some of these issues have been raised- and I will admit, I've learned a tremendous amount due to my participation over the years here.
Here's where I feel the interpretation of scientific data regarding reflector images, and Fancy Shaped Diamonds sometimes falls short.
In the case of the ASET chart Garry posted, it's quite clear which is considered better by whoever put the chart together.

My contention is that once a measurement is taken, you get a scientific result. Like a millimeter size, or a weight. That's an objective measurement. Once someone, or a a group of people categorize this objective result, it becomes a subjective result. Like a poll.
Who gets to say which of these scientific measurements are "excellent" as opposed to Very Good. The only method of truly describing them in a scientific manner is objective measurements.

When someone is deciding which type of light performance is "better" by virtue of a subjective label, like "excellent" or even "0" it is no longer merely a scientific measurement. It is an evaluation of a scientific measurement. Who gets to say where the line between 0 and 1 is on AGS scale?
Subjective.
IN fact, this could be a debate on the weight a lab should place on human observation at all.
Which goes to a real main point- beauty.
The fact is, not all experts in the field will agree that an AGS0 princess cut is a better cut than a slightly spreadier stone, which will show more green in an ASET, and fall short of 0 by AGSL standards.

We agree that there's a majority of poorly cut fancy shapes on the market- really nice ones are quite hard to find.
We agree that consumers need tools to assist them.

I'm suggesting the labels given on the chart above- from the page Garry posted represent a subjective opinion, giving us a higher possibility of misinterpretation opposed to a numerical value.

Here's an example of typical mis-read.
A truly well cut "crushed ice" Radiant cut will have a very "disorganized" ASET- and may indeed show leakage in the table. Yet the real life look of the diamond does not correlate the white areas in the ASET with anything negative at all.
On such stones large concentrations of red can be very problematic, in my opinion. The reason I say this is that in real life, the red areas on an otherwise nice crushed ice stone may appear dark.
Bryan, I would suggest this to you, as a highly regarded seller. If you have a client looking for a princes cut, and they are led to believe red is better- which is reasonable for people who read and post a lot to say, they may choose a stone with red for the wrong reasons, and be more likely to return.
I think its fair to say that any vendor participating in this forum regularly is dedicated to transparency for everyone's benefit
When we're assigning all these subjective titles to objective measurements, how much weight is placed on spread for the weight?


Here's a scientific fact.
Take a piece of rough, 10 carats. The weight and price of this rough are established, objective, scientific measurements.
The size, weight, and price of the resultant polished diamond is also an objective measurement.
What if the choice was a 7.5ct "Crushed Ice" stone- getting "Fair" ASET based on the chart above, or a 6ct stone which will get "Excellent" ASET ratings based on the chart above.
A well designed and cut "crushed ice" stone has a lot more light bounces. Such a stone shows a lot of green and some scattering of white. Not a lot of red in the well cut ones IMO. Such a stone can be very brilliant through a fairly wide range of viewing angles. The leakage identified in the ASET is compensated for when you move the diamond. We all agree large areas of leakage will cause windows that are generally undesirable in modern cut non specialty diamonds ( find me a non leaky horse head
However all diamonds will exhibit some leakage. In many cases leakage identified on ASET is not possible to see in real life.


So, for the same price a consumer can buy a well cut 11.5mm 7.5ct stone, or an AGSL0 cut grade 6.00ct stone, which will be noticeably smaller. The real world spread on weight a mm size might even be greater in many cases.
Hypothetical numbers, but real world truths.
I totally get the beauty of an AGSL0 fancy shape cut grade stone- and they are definitely worth the money for someone looking for that type of look.
The science that identifies larger brighter flashes with ASET is valid. Labeling it is the question.
And the science behind well cut crushed ice ( there- I've said it a few times already) is also remarkable, and can produce a stunning diamond.
When AGSL designates 0 cut grades for fancy shapes- how much weight is placed on spread?

David,
Thank you for taking the time to lay out your position. But again, I don't quite get the main point. You seem to be arguing against subjectivity, claiming that because established grading systems (including scientifically vetted ones) contain labels such as Excellent or Ideal, that they are somehow misleading.

Your comments, at the same time, contain multiple references to your own subjective judgments (labels). You talk about crushed ice with dominant green in aset that are "stunning", and about stones with ASET showing alot of leakage that you don't see in real life. And you reference tones with alot of red in aset that "look dark" to you. So you have your own standards and methodologies and you are entitled to your own value judgments and to communicate them with your own adjectives. So the answer to the question of who gets to assign the labels is obviously the entity creating the standard.

There is nothing misleading about it if you understand the underpinnings of whatever standard you are evaluating. For instance, GIA has a cut grading standard for rounds. Many people believe the top grade is too broad and they therefore seek more information to help select the truly excellent from those at the margins. Conversely, some people may find the AGS princess standard to be too strict and they see as perfectly acceptable diamonds that will not make the top grade in that standard.

You make a special point about spread and it certainly is important and it is definitely factored in to both the GIA and AGS systems. But spread alone will not get you a top grade from either lab. It is only one factor that is evaluated in relation to brightness, dispersion, leakage, contrast, and finish. In fact, the new tools available today, especially ray tracing technology, has finally opened our eyes to the fact that we can get so much more beauty out of a diamond by not cutting with an emphasis on the traditional goals of weight retention and/or spread.

And those tools and new ones yet to be developed offer the promise of taking us much further in our understanding. The work that Garry referred to regarding human perception, binocular rivalry and such, is kind of mind blowing.

So, on this basic premise I will agree with you: at some level of any diamond grading standard there are going to be decisions, value judgments, that can be construed to be 'subjective'. After all, the labs exist to help consumers understand the relative value of the diamond under consideration. Whether you find a particular standard useful may to some extent depend on whether you agree with the methodology of how those judgments were arrived at. On the other hand, you may find a system useful even if you think the labels put on it are not perfect, such as the example above of GIA Ex. This system is still used very effectively, by consumers who feel the label is too broad, as a filter to narrow down options to take a further look. And the same is even more true in the case of AGS Princess, since GIA reports are of little value in assessing light performance in this very popular shape.

 

[Rockdiamond]

Amazing, thought provoking discussion- thank you all.
To Yassss- and RandG- thank you very much for your words of support.
Voicing an opinion which is different than so many others is not easy- but I do feel it's important.

Bryan- you raise some great points- I'd touch on this one.
You referred to my use of the word "stunning" to describe a particular type of diamond that pleases my eyes at a subjective label.
Let's say we had a cut grade on our site. Say the top grade was called "Stunning" then we'd have "Kind of pretty but not so sparkly" the lowest grade is called "Looks like the back end of a dog"
How would shoppers react? Does it sound at all scientific?
Now lets change my subjective terms to Excellent, Very Good good and fair.
In both cases there's ZERO scientific, objective measurement.
IN one case, it's clearly just my opinion, taken with as much of a grain of salt as you please.
In the second case, consumers are led to believe that there's a scientific basis to the cut grade.
This isn't hypothetical- it's happening right now on some of the largest diamond selling sites advertising cut grades on stones based on.....well who knows.


I would suggest that the chart I posted of ASET - which has four images labeled EX- Fair is doing the very same thing. Therefore, people advising others based on education gleaned from that chart will be giving false negative- and also false positives based on the subjective grades listed on the chart.
If shoppers understood the benefits and liabilities of the different types of cuts better, they'd make better choices FOR THEMSELVES- based on their own subjective eye for beauty, size, brilliance, fire, scintillation and price.
Terms like EX when misused do not help consumers.

 

[Diamond_Hawk]

I don't like it, but one thing that does become apparent with no backlighting is that the darkzones stand out better. i.e. when the blue (possible obstruction) and the black (leakage) zones are side by side then you wll likely see a big dead dark area frequently in that diamond.

blue = possible obstruction - but AGS are doing a disservice by using such a large blue zone because obstruction is no where near the issue that they make it out to be.

In the recent series of articles starting with the Australian Gemmologist, we point out based on Hardings 1980's work, that obstruction models are designed for Cyclops. But most people I know have 2 eyes and maximum obuscration of illumination is 8 degrees, not 32.5. (Bruce used 10 or 12 degrees from the same side eye to a lamp though)

Garry, I understand your point, but obstruction seems pretty variable to me, mono or stereo. It depends on who is looking, how close they are to the diamond, how much light comes over & around them, how much their body obstructs the light - and now whether they have an eye-patch. I don’t have a problem with the AGS metric because (in-lab) they’re running 30 and 40 degrees of blue. While strict, it parallels real life I think. When most people examine a diamond for the first time – like when a friend holds out her hand to show it to them – they tend to hold and look at it from around 10 inches, obstructing right around that much light with head and body. Arguable, of course.

I think backlit versus non-backlit is more black and white (literally ). I find the backlit ASET to provide a stark contrast between the ‘white’ of leakage and the blue, red, or green of light returning to the viewer. When you view diamonds in non-backlit ASET a case can be made that one could be ‘fooled’ into mistaking black leakage for a light-returning contrast area (this is the same point you were making, but with the distinction that the viewer may see the black as blue rather than vice-versa).

 

[Texas Leaguer]

Amazing, thought provoking discussion- thank you all.
To Yassss- and RandG- thank you very much for your words of support.
Voicing an opinion which is different than so many others is not easy- but I do feel it's important.

Bryan- you raise some great points- I'd touch on this one.
You referred to my use of the word "stunning" to describe a particular type of diamond that pleases my eyes at a subjective label.
Let's say we had a cut grade on our site. Say the top grade was called "Stunning" then we'd have "Kind of pretty but not so sparkly" the lowest grade is called "Looks like the back end of a dog"

How would shoppers react? They wouldn't be likely to buy the dogs, and perhaps they shouldn't. Perhaps if they didn't cutters would step up their game. Does it sound at all scientific? No. Is it? You indicated it was simply based on what pleases your eyes.

Now lets change my subjective terms to Excellent, Very Good good and fair.
In both cases there's ZERO scientific, objective measurement.
IN one case, it's clearly just my opinion, taken with as much of a grain of salt as you please.
In the second case, consumers are led to believe that there's a scientific basis to the cut grade. Why do you assume they are led to believe it is scientific? Just because it uses labels such as Excellent, Very Good, etc? Must all grading standards now eliminate use of Excellent, Very Good, Fair and Poor from their systems to keep from misleading consumers?

This isn't hypothetical- it's happening right now on some of the largest diamond selling sites advertising cut grades on stones based on.....well who knows. That's the real world David. Marketing has gone on for eons and will continue. Some claims are proven, or at least based upon solid foundations, others are based upon "trust me, its a great deal". You consider the source, evaluate the information and deal with those who provide you with what you need to feel comfortable and confident.


I would suggest that the chart I posted of ASET - which has four images labeled EX- Fair is doing the very same thing. Therefore, people advising others based on education gleaned from that chart will be giving false negative- and also false positives based on the subjective grades listed on the chart. Not if they understand something of the foundations of the presentation.

If shoppers understood the benefits and liabilities of the different types of cuts better, they'd make better choices FOR THEMSELVES- based on their own subjective eye for beauty, size, brilliance, fire, scintillation and price.
Terms like EX when misused do not help consumers.Any term misused is a disservice to the customer.

David,
Please see my responses above in bold above. Unfortunately, I am as unclear as ever as to the real point you are trying to make.

If you are saying we need to look at the actual diamond, we agree. If you are saying there may be there are certain assumptions in some of the grading standards that you disagree with, and that you have your own preferences based upon years of experience and looking at thousands of diamonds, I get that.

But, If you are just continuing to try to sand away diamond cut grading standards where ever you find them until there is nothing left BUT the human eye, I think that is a disservice to the consumer. Like I say, I am unsure of exactly what your point is so forgive me if I misunderstand you.

 

[Rockdiamond]

Bryan- quick response:
I am not questioning the validity or usefulness of AGSL or GIA grading.
Just like every other educated diamond buyer, I depend on either of these lab's grading procedures and standards.
Part of the strength of this forum is to assist consumers in determining what is a "sales pitch" and what is sound practice to follow when buying a diamond.
I'm sure we all agree that using non GIA or AGSL grading to determine a diamond's value leads to incorrect results. I find it pretty distasteful that a well known lab can call a diamond H color that grades accurately as an L. They are not doing this "by accident"
This is my life's work, and that bothers me.

If any website decided to use "0" instead of "EX" for their top cut grade, how would you feel about that?
Part of this discussion was spurred by the fact that some labels that actually DO mean something - such as cut grade terminology issued by GIA an AGSL in particular.
If Joe Shmoe Diamond seller wants to throw around labels like "Excellent", that's their problem.
This is a place where we can cut through that sort of sales pitch.

 

[Rockdiamond]

A well designed and cut "crushed ice" stone has a lot more light bounces. Such a stone shows a lot of green and some scattering of white. Not a lot of red in the well cut ones IMO. Such a stone can be very brilliant through a fairly wide range of viewing angles. The leakage identified in the ASET is compensated for when you move the diamond. We all agree large areas of leakage will cause windows that are generally undesirable in modern cut non specialty diamonds ( find me a non leaky horse head
However all diamonds will exhibit some leakage. In many cases leakage identified on ASET is not possible to see in real life.

David,
1) Crushed Ice cuts have much less Fire than Good Cuts with big VF's.

Serg- Neither stone is actually "ignited". Fire is a concept phrase created to describe a certain quality of light reflected off a diamond. I agree that Crushed ice stones will have flashes that are somewhat less bright. If you want to call that "Fire", agreed.

2) Crushed Ice cuts looks much darker in Light Environment with black background then in typical LAB environment to check color and clarity.( where is a lot light from pavilion)/
Modern Crushed Ice cuts may compete and even Win in Brightness in compare with Cuts with Big Virtual Facets only in light environment with a lot of light from Pavilion.
In most Jeweller pieces Crushed Ice cut have much less Brightness .
Serg- I strongly disagree. Both cuts are compromised in certain lighting conditions. The best cut modern brilliant looks dark in light that makes a crushed ice stone come alive- natural light.
Everybody may easy check it.

There is not technology to produce Crushed Ice cut without strong Leakage . ( may be it is possible design such cut but it is not possible to produce). But even if you may produce Crushed Ice without Leakage it has not Fire. It looks as many Melee diamonds.
If you need just Brightness then Buy Cluster of Melee diamonds.
7Ct well cut diamond has to have good balance between Fire, Brilliancy and Scintillation . 7ct Crushes Cut has not such balance.
what is reason to pay for additional 1.5ct and miss Fire?

Serg- all due respect, but the entire last paragraph is way off base.
A 7 ct well cut crushed ice radiant looks NOTHING like pave, or cluster of melee diamonds. It's like a bottomless pit.
Since the light bounces around so much it's like a house of mirrors. You can't see where the light is coming from or being reflected off of.
Yes, each flash coming off the crushed ice stone is less bright than the larger ones coming off a well cut stone showing a well defined red pattern in ASET.
But sometimes 1000 greens is as desirable than 8 reds.
How do you like your sparkle?
Less flashes that are more bright, or infinitely more flashes, slightly less bright.

 

[Texas Leaguer]

Bryan- quick response:
I am not questioning the validity or usefulness of AGSL or GIA grading.
Just like every other educated diamond buyer, I depend on either of these lab's grading procedures and standards.
Part of the strength of this forum is to assist consumers in determining what is a "sales pitch" and what is sound practice to follow when buying a diamond.
I'm sure we all agree that using non GIA or AGSL grading to determine a diamond's value leads to incorrect results. I find it pretty distasteful that a well known lab can call a diamond H color that grades accurately as an L. They are not doing this "by accident"
This is my life's work, and that bothers me.

If any website decided to use "0" instead of "EX" for their top cut grade, how would you feel about that?
Part of this discussion was spurred by the fact that some labels that actually DO mean something - such as cut grade terminology issued by GIA an AGSL in particular.
If Joe Shmoe Diamond seller wants to throw around labels like "Excellent", that's their problem.
This is a place where we can cut through that sort of sales pitch.

David,
Thanks for the clarifications. As you told DiamondHawk earlier, I think we are in agreement on more things than we are in dissagreement about.

Regarding how I would feel if some diamond dealer uses a designation of "0" on his site rather than "Ex" for his top grade, I understand your point, but this is not a new issue. The answer is Consider the source - Consider the supporting evidence. If their "0" category had all AGS 0 certs, I would of course be fine with it.

Let's face it, liberties are taken all the time. There are well respected sellers offering "Signature Ideal Princess cuts" that do not come close to AGS Ideal. They have GIA certs but very few of them are even Ex Ex! In my opinion this is an ethical issue, not a lab grading standards or nomenclature issue.

This problem goes back to before the GIA started the grading system. There were companies using A,B,C grades, AAA,AA,A grades, and A, AA,AAA grades. To try to differentiate and avoid confusion with those marketers GIA chose to start the color scale at D.

The good news is that the consumer is empowered today by unprecedented access to information. Not only can they verify information about the products being offered, they can easily review sellers reputations. This forum is a prime example of the access consumers have to information and expertise and to highly valued prosumer guidance.

Do I wish that every seller was honest and played by the same rules. Absolutely. Do I think it would benefit consumers if there was one unified, scientifically sound, 100% accurate grading system for all diamonds including cut grading for all? Indeed I would. But we don't live in that world. At least not yet. The best we can do is our part to give the best info and advice that we can and operate with full integrity.

 

[Serg]

A well designed and cut "crushed ice" stone has a lot more light bounces. Such a stone shows a lot of green and some scattering of white. Not a lot of red in the well cut ones IMO. Such a stone can be very brilliant through a fairly wide range of viewing angles. The leakage identified in the ASET is compensated for when you move the diamond. We all agree large areas of leakage will cause windows that are generally undesirable in modern cut non specialty diamonds ( find me a non leaky horse head
However all diamonds will exhibit some leakage. In many cases leakage identified on ASET is not possible to see in real life.

David,
1) Crushed Ice cuts have much less Fire than Good Cuts with big VF's.

Serg- Neither stone is actually "ignited". Fire is a concept phrase created to describe a certain quality of light reflected off a diamond. I agree that Crushed ice stones will have flashes that are somewhat less bright. If you want to call that "Fire", agreed.

2) Crushed Ice cuts looks much darker in Light Environment with black background then in typical LAB environment to check color and clarity.( where is a lot light from pavilion)/
Modern Crushed Ice cuts may compete and even Win in Brightness in compare with Cuts with Big Virtual Facets only in light environment with a lot of light from Pavilion.
In most Jeweller pieces Crushed Ice cut have much less Brightness .
Serg- I strongly disagree. Both cuts are compromised in certain lighting conditions. The best cut modern brilliant looks dark in light that makes a crushed ice stone come alive- natural light.
Everybody may easy check it.

There is not technology to produce Crushed Ice cut without strong Leakage . ( may be it is possible design such cut but it is not possible to produce). But even if you may produce Crushed Ice without Leakage it has not Fire. It looks as many Melee diamonds.
If you need just Brightness then Buy Cluster of Melee diamonds.
7Ct well cut diamond has to have good balance between Fire, Brilliancy and Scintillation . 7ct Crushes Cut has not such balance.
what is reason to pay for additional 1.5ct and miss Fire?

Serg- all due respect, but the entire last paragraph is way off base.
A 7 ct well cut crushed ice radiant looks NOTHING like pave, or cluster of melee diamonds. It's like a bottomless pit.
Since the light bounces around so much it's like a house of mirrors. You can't see where the light is coming from or being reflected off of.
Yes, each flash coming off the crushed ice stone is less bright than the larger ones coming off a well cut stone showing a well defined red pattern in ASET.
But sometimes 1000 greens is as desirable than 8 reds.
How do you like your sparkle?
Less flashes that are more bright, or infinitely more flashes, slightly less bright.

Dave,
1) what is Fire for you?
your Comments about Fire looks very strange for me. Please Clarify you Fire definition
2) re:Serg- I strongly disagree. Both cuts are compromised in certain lighting conditions. The best cut modern brilliant looks dark in light that makes a crushed ice stone come alive- natural light

You missed main statement. please check it again.

Crushed Ice cuts do not look so good if lights sources are absent from pavilion side.
It is very easy to check and I checked it several times with many observers.
Many observers preferred Crushed Ice Cushion in Illumination with bright white background, but same observers did not like same diamond if I blocked light from pavilion side. It is very easy to check.
As I remember I suggested similar test for you for round cut with strong leakage several years( during long discussions about 60/60, Leakage , IS), but You never answered.
If you do not like to do such tests (verification), I do not like to spoil my time to repeat same again and again.

 

[Rockdiamond]

Serg- please have a look at the top sellers in the world of Fancy Colored Diamonds.
Please notice how the most sought after fancy yellow radiant or cushion cut diamonds are cut ( crushed ice)
Please notice how these diamonds are set- in many cases the pavilion is obstructed by parts of the ring- and many times on purpose.
Look at the resulting rings.
Maybe you find this type of look to be sub-standard.
Maybe the people you showed your test felt the same way.
But Harry Winston,Tiffany, Graff, and many others are finding far different results in the real world.
The look we're calling "Crushed ice" has found wide acceptance - even if the pavilion is obstructed.
The finest fancy colored stones- the most desirable fancy colored diamonds in the world are cut this way.

Maybe there is something about this look we can classify as desirable?
Anything?

 

[Texas Leaguer]

Serg- please have a look at the top sellers in the world of Fancy Colored Diamonds.
Please notice how the most sought after fancy yellow radiant or cushion cut diamonds are cut ( crushed ice)
Please notice how these diamonds are set- in many cases the pavilion is obstructed by parts of the ring- and many times on purpose.
Look at the resulting rings.
Maybe you find this type of look to be sub-standard.
Maybe the people you showed your test felt the same way.
But Harry Winston,Tiffany, Graff, and many others are finding far different results in the real world.
The look we're calling "Crushed ice" has found wide acceptance - even if the pavilion is obstructed.
The finest fancy colored stones- the most desirable fancy colored diamonds in the world are cut this way.

Maybe there is something about this look we can classify as desirable?
Anything?

David,
by no means am I qualified to answer for Serg. But it seems to me you are conflating two different issues.
With fancy colored diamonds, the value is much more driven by depth of color than by light performance. In fact, too much brightness can diminish the apparent depth of color, so moderating brightness by cutting style and by the setting technique is often desirable.
So you often see fancy yellows for instance closed in with molded 24k bottoms to intensify the appearance of the color. But since I am quite sure you know this, I have to question the motivation of your comments.

 

[RADIANTMAN]

A friend just pointed me to this extremely interesting thread so I figured I'd chime in with my 2 cents. I fully agree with David, and I think with everyone else here that with fancy shapes there is no substitute for seeing the diamond. ASET scans provide valuable data that, if interpreted correctly by an expert, can ( when considered together with other data like a Sarin report and a photo), give an expert a a pretty good idea of what the diamond might look like if he/she got to see it. it is, however, even to the expert who knows how to interpret the data, no substitute fore the human eye which provides the best data of all and ultimately the only data that matters.

I also agree with David that the "red is better" mantra is a misleading oversimplification. Too much red around the culet of a radiant cut ASET scan is an indication that there will be a concentration of black around the culet, a sign of a poorly cut diamond that has the facets forming the culet on too high an angle. I recut such diamonds all the time likely resulting in a much more attractive radiant but very possibly with an ASET scan that some commentators here might consider less desirable because it has less of a concentration of red.

It should also be remembered that the entire concept of the ASET is based on the idea that the most important light is the light that comes toward the diamond from above. That is certainly true when the ring is on your finger and you are holding it up to admire it yourself. But when the diamond is actually being worn and your arms are moving around, the diamond spends relatively little time with the table pointed to the sky. Most of the time the overhead light will actually be oriented toward the side of the diamond not the top.

As a tool for consumers the ASET is, in my opinion, of limited value with respect to fancy shapes because consumers (and frankly some of those who provide advice to others on this site) simply do not have the expertise to properly interpret the scan and that expertise cannot be gained simply by reviewing a few sample princess cut ASETs shown as examples. You certainly can't extrapolate from a princess to a radiant because the cuts are intended to reflect light differently. Relying on a misinterpretation of data is worse than not having the data at all and even well meaning "experts" without alternate agendas too often provide incorrect or over simplified interpretations simply because they are not as "expert" as they think they are.

The best substitute for your own eyes, if you are buying sight unseen, is buying from someone you trust, trusting their eyes as a substitute for your own.

 

[Rockdiamond]

HI Bryan,
Obviously I am very familiar with the aspects that make Fancy Colored Diamonds desirable.
And I do agree with a lot of what you wrote.
When a diamond is "too bright" you don't see the color as well- such as is the case in larger round diamonds.
Where we strongly disagree is your statement that Fancy Colored Diamonds are NOT judged on light performance.
Just like with colorless diamonds, there's super well cut FCD's and others that are less so.
Unlike colorless, a poorly cut stone with amazing color may still be desirable to a lot of buyers- but that does not mean that super well cut FCD's don't bring a premium- they do.
Many people love bright colors- therefore superior light performance is what they seek.
Part of what I love so much about the light performance of a well cut FCD is the ability to be incredibly bright, yet yellow at the same time.
Poorly cut Vivid Yellow stones can look dull- any color of diamond can look dull if it's really badly cut.

In terms of my motivation in this- or any discussion here on PS- it is to add my perspective. Clearly it's from a different viewpoint than most who post here. Hopefully it adds context.
A large part of my job is buying diamonds. I do it daily. Mostly Fancy Shapes.
Garry and Serg are designing technologies that will benefit consumers and the trade alike. Stan, Yoram and Paul are Diamond cutters
When any of us post the best we can do is post from the heart.
I am happy to see Stan here- because I think he can add a lot to a discussion like this.
More perspective=better perspective for all.

 

[Texas Leaguer]

A friend just pointed me to this extremely interesting thread so I figured I'd chime in with my 2 cents. I fully agree with David, and I think with everyone else here that with fancy shapes there is no substitute for seeing the diamond. ASET scans provide valuable data that, if interpreted correctly by an expert, can ( when considered together with other data like a Sarin report and a photo), give an expert a a pretty good idea of what the diamond might look like if he/she got to see it. it is, however, even to the expert who knows how to interpret the data, no substitute fore the human eye which provides the best data of all and ultimately the only data that matters.

I also agree with David that the "red is better" mantra is a misleading oversimplification. Too much red around the culet of a radiant cut ASET scan is an indication that there will be a concentration of black around the culet, a sign of a poorly cut diamond that has the facets forming the culet on too high an angle. I recut such diamonds all the time likely resulting in a much more attractive radiant but very possibly with an ASET scan that some commentators here might consider less desirable because it has less of a concentration of red.

It should also be remembered that the entire concept of the ASET is based on the idea that the most important light is the light that comes toward the diamond from above. That is certainly true when the ring is on your finger and you are holding it up to admire it yourself. But when the diamond is actually being worn and your arms are moving around, the diamond spends relatively little time with the table pointed to the sky. Most of the time the overhead light will actually be oriented toward the side of the diamond not the top.

As a tool for consumers the ASET is, in my opinion, of limited value with respect to fancy shapes because consumers (and frankly some of those who provide advice to others on this site) simply do not have the expertise to properly interpret the scan and that expertise cannot be gained simply by reviewing a few sample princess cut ASETs shown as examples. You certainly can't extrapolate from a princess to a radiant because the cuts are intended to reflect light differently. Relying on a misinterpretation of data is worse than not having the data at all and even well meaning "experts" without alternate agendas too often provide incorrect or over simplified interpretations simply because they are not as "expert" as they think they are.

The best substitute for your own eyes, if you are buying sight unseen, is buying from someone you trust, trusting their eyes as a substitute for your own.

Stan,
Nice to have you aboard. Your expertise is a tremendous asset to this forum. No pun intended!

I would just point out that nobody has suggested that there is a substitute for seeing a fancy shape with your eyes. Nor has anyone downplayed the wisdom of dealing with an experienced expert with a highly trained eye.

And everyone also agrees that fancy shape asets have different signatures and that different people seem to like different flavors. And that interpreting asets properly in order to be able to predict how a stone might perform is therefore something that takes experience.

We can all benefit from your knowledge and you can help us understand the unique aspects and nuances of fancies including interpretation o aset images.

It's great to see you post here.

 

[Garry H (Cut Nut)]

Serg- please have a look at the top sellers in the world of Fancy Colored Diamonds.
Please notice how the most sought after fancy yellow radiant or cushion cut diamonds are cut ( crushed ice)
Please notice how these diamonds are set- in many cases the pavilion is obstructed by parts of the ring- and many times on purpose.
Look at the resulting rings.
Maybe you find this type of look to be sub-standard.
Maybe the people you showed your test felt the same way.
But Harry Winston,Tiffany, Graff, and many others are finding far different results in the real world.
The look we're calling "Crushed ice" has found wide acceptance - even if the pavilion is obstructed.
The finest fancy colored stones- the most desirable fancy colored diamonds in the world are cut this way.

Maybe there is something about this look we can classify as desirable?
Anything?

That would be a huge segue to Sergey David.

He is a worlds leading expert on FCD cutting and you do not answer his question with a change of topic?

 

[Garry H (Cut Nut)]

A friend just pointed me to this extremely interesting thread so I figured I'd chime in with my 2 cents. I fully agree with David, and I think with everyone else here that with fancy shapes there is no substitute for seeing the diamond. ASET scans provide valuable data that, if interpreted correctly by an expert, can ( when considered together with other data like a Sarin report and a photo), give an expert a a pretty good idea of what the diamond might look like if he/she got to see it. it is, however, even to the expert who knows how to interpret the data, no substitute fore the human eye which provides the best data of all and ultimately the only data that matters.

I also agree with David that the "red is better" mantra is a misleading oversimplification. Too much red around the culet of a radiant cut ASET scan is an indication that there will be a concentration of black around the culet, a sign of a poorly cut diamond that has the facets forming the culet on too high an angle. I recut such diamonds all the time likely resulting in a much more attractive radiant but very possibly with an ASET scan that some commentators here might consider less desirable because it has less of a concentration of red.

It should also be remembered that the entire concept of the ASET is based on the idea that the most important light is the light that comes toward the diamond from above. That is certainly true when the ring is on your finger and you are holding it up to admire it yourself. But when the diamond is actually being worn and your arms are moving around, the diamond spends relatively little time with the table pointed to the sky. Most of the time the overhead light will actually be oriented toward the side of the diamond not the top.

As a tool for consumers the ASET is, in my opinion, of limited value with respect to fancy shapes because consumers (and frankly some of those who provide advice to others on this site) simply do not have the expertise to properly interpret the scan and that expertise cannot be gained simply by reviewing a few sample princess cut ASETs shown as examples. You certainly can't extrapolate from a princess to a radiant because the cuts are intended to reflect light differently. Relying on a misinterpretation of data is worse than not having the data at all and even well meaning "experts" without alternate agendas too often provide incorrect or over simplified interpretations simply because they are not as "expert" as they think they are.

The best substitute for your own eyes, if you are buying sight unseen, is buying from someone you trust, trusting their eyes as a substitute for your own.

Hi Radiant man.
welcome back after what seems a long break.
I think you underestimate the ability of many outside our industry to learn what is useful for them.
In fact it would be insulting to many on this forum who are more expert than experts.
A sarin report is quite possibly a complete waste of time for experts and novices in the case of fancy shapes - compared to a Sarin .srn or other .stl files in the hands of people who know what to do with it. Sadly, I think I can count on one hand the number of people selling diamonds (away from this place) who even know what a 3D file is!

 

[Texas Leaguer]

HI Bryan,
Obviously I am very familiar with the aspects that make Fancy Colored Diamonds desirable.
And I do agree with a lot of what you wrote.
When a diamond is "too bright" you don't see the color as well- such as is the case in larger round diamonds.
Where we strongly disagree is your statement that Fancy Colored Diamonds are NOT judged on light performance.
Just like with colorless diamonds, there's super well cut FCD's and others that are less so.
Unlike colorless, a poorly cut stone with amazing color may still be desirable to a lot of buyers- but that does not mean that super well cut FCD's don't bring a premium- they do.
Many people love bright colors- therefore superior light performance is what they seek.
Part of what I love so much about the light performance of a well cut FCD is the ability to be incredibly bright, yet yellow at the same time.
Poorly cut Vivid Yellow stones can look dull- any color of diamond can look dull if it's really badly cut.

In terms of my motivation in this- or any discussion here on PS- it is to add my perspective. Clearly it's from a different viewpoint than most who post here. Hopefully it adds context.
A large part of my job is buying diamonds. I do it daily. Mostly Fancy Shapes.
Garry and Serg are designing technologies that will benefit consumers and the trade alike. Stan, Yoram and Paul are Diamond cutters
When any of us post the best we can do is post from the heart.
I am happy to see Stan here- because I think he can add a lot to a discussion like this.
More perspective=better perspective for all.

David,
I would appreciate it if when you quote me you include my actual words. I did not say that fancy colors are not judged on light performance. This is what I said:

"With fancy colored diamonds, the value is much more driven by depth of color than by light performance."

Nor did I suggest that poorly cut stones are as good as well cut stones. Incredible skill is needed in crafting a fancy color to gain the optimal beauty.

The distinction I made had to do entirely with your decision to introduce fancy color into the discussion as rebuttal to Serg's statements. You are comparing apples and oranges there to a significant extent. And you know that.

 

[Rockdiamond]

Actually, I find that light performance has a tremendous amount to do with the value of a fancy colored diamond.
I also noticed quite a few of the advances in colorless cutting technology making their way to fancy colored diamond cutting,
Things like higher crowns and smaller tables
This relate strongly to this discussion because of how these changes affect the diamonds light performance. Not always as you might expect.

 

[RandG]

A friend just pointed me to this extremely interesting thread so I figured I'd chime in with my 2 cents. I fully agree with David, and I think with everyone else here that with fancy shapes there is no substitute for seeing the diamond. ASET scans provide valuable data that, if interpreted correctly by an expert, can ( when considered together with other data like a Sarin report and a photo), give an expert a a pretty good idea of what the diamond might look like if he/she got to see it. it is, however, even to the expert who knows how to interpret the data, no substitute fore the human eye which provides the best data of all and ultimately the only data that matters.

I also agree with David that the "red is better" mantra is a misleading oversimplification. Too much red around the culet of a radiant cut ASET scan is an indication that there will be a concentration of black around the culet, a sign of a poorly cut diamond that has the facets forming the culet on too high an angle. I recut such diamonds all the time likely resulting in a much more attractive radiant but very possibly with an ASET scan that some commentators here might consider less desirable because it has less of a concentration of red.

It should also be remembered that the entire concept of the ASET is based on the idea that the most important light is the light that comes toward the diamond from above. That is certainly true when the ring is on your finger and you are holding it up to admire it yourself. But when the diamond is actually being worn and your arms are moving around, the diamond spends relatively little time with the table pointed to the sky. Most of the time the overhead light will actually be oriented toward the side of the diamond not the top.

As a tool for consumers the ASET is, in my opinion, of limited value with respect to fancy shapes because consumers (and frankly some of those who provide advice to others on this site) simply do not have the expertise to properly interpret the scan and that expertise cannot be gained simply by reviewing a few sample princess cut ASETs shown as examples. You certainly can't extrapolate from a princess to a radiant because the cuts are intended to reflect light differently. Relying on a misinterpretation of data is worse than not having the data at all and even well meaning "experts" without alternate agendas too often provide incorrect or over simplified interpretations simply because they are not as "expert" as they think they are.

The best substitute for your own eyes, if you are buying sight unseen, is buying from someone you trust, trusting their eyes as a substitute for your own.

Excellent post! I sometimes see novice consumers coming to this forum, dissuaded by "experts" from beautiful fancy cut stones because the vendor does not offer an ASET, the ASET/specs do not meet some arbitrary standard of "ideal" or because there is an assumption based on a few photos that a stone does not merit further review only to then be pushed to vendors who offer ASET images, to the exclusion of those who don't. This is my only objection to the extensive marketing of ASET use on this site. It's a tool, not the exclusive basis in which to choose a fancy cut diamond. Cut is important, but no more than any other factor used to judge a stone, with your eyes being the best judge. Modern day "ideal" standards are not for everyone, nor should they be held out as the benchmark for successful diamond buying. I wouldn't own a single stone if they did!

 

[Garry H (Cut Nut)]

A friend just pointed me to this extremely interesting thread so I figured I'd chime in with my 2 cents. I fully agree with David, and I think with everyone else here that with fancy shapes there is no substitute for seeing the diamond. ASET scans provide valuable data that, if interpreted correctly by an expert, can ( when considered together with other data like a Sarin report and a photo), give an expert a a pretty good idea of what the diamond might look like if he/she got to see it. it is, however, even to the expert who knows how to interpret the data, no substitute fore the human eye which provides the best data of all and ultimately the only data that matters.

I also agree with David that the "red is better" mantra is a misleading oversimplification. Too much red around the culet of a radiant cut ASET scan is an indication that there will be a concentration of black around the culet, a sign of a poorly cut diamond that has the facets forming the culet on too high an angle. I recut such diamonds all the time likely resulting in a much more attractive radiant but very possibly with an ASET scan that some commentators here might consider less desirable because it has less of a concentration of red.

It should also be remembered that the entire concept of the ASET is based on the idea that the most important light is the light that comes toward the diamond from above. That is certainly true when the ring is on your finger and you are holding it up to admire it yourself. But when the diamond is actually being worn and your arms are moving around, the diamond spends relatively little time with the table pointed to the sky. Most of the time the overhead light will actually be oriented toward the side of the diamond not the top.

As a tool for consumers the ASET is, in my opinion, of limited value with respect to fancy shapes because consumers (and frankly some of those who provide advice to others on this site) simply do not have the expertise to properly interpret the scan and that expertise cannot be gained simply by reviewing a few sample princess cut ASETs shown as examples. You certainly can't extrapolate from a princess to a radiant because the cuts are intended to reflect light differently. Relying on a misinterpretation of data is worse than not having the data at all and even well meaning "experts" without alternate agendas too often provide incorrect or over simplified interpretations simply because they are not as "expert" as they think they are.

The best substitute for your own eyes, if you are buying sight unseen, is buying from someone you trust, trusting their eyes as a substitute for your own.

Excellent post! I sometimes see novice consumers coming to this forum, dissuaded by "experts" from beautiful fancy cut stones because the vendor does not offer an ASET, the ASET/specs do not meet some arbitrary standard of "ideal" or because there is an assumption based on a few photos that a stone does not merit further review only to then be pushed to vendors who offer ASET images, to the exclusion of those who don't. This is my only objection to the extensive marketing of ASET use on this site. It's a tool, not the exclusive basis in which to choose a fancy cut diamond. Cut is important, but no more than any other factor used to judge a stone, with your eyes being the best judge. Modern day "ideal" standards are not for everyone, nor should they be held out as the benchmark for successful diamond buying. I wouldn't own a single stone if they did!

RandG, as one who sells ASET, and someone with a lot of experiance using it and ideal-scope to buy diamonds, it is a rejection tool. If a vendor refuses to supply ASET images it is very often the case that the stones would and should be rejected based on the ASET and its interpretaions here on PS. However that said, there are examples where some consumers give the wrong advice - no doubt. Its something that I ask all people to bring to mine and other experianced posters attention so we can intercede and help educate the prosumers.

 

[Serg]

Serg- please have a look at the top sellers in the world of Fancy Colored Diamonds.
Please notice how the most sought after fancy yellow radiant or cushion cut diamonds are cut ( crushed ice)
Please notice how these diamonds are set- in many cases the pavilion is obstructed by parts of the ring- and many times on purpose.
Look at the resulting rings.
Maybe you find this type of look to be sub-standard.
Maybe the people you showed your test felt the same way.
But Harry Winston,Tiffany, Graff, and many others are finding far different results in the real world.
The look we're calling "Crushed ice" has found wide acceptance - even if the pavilion is obstructed.
The finest fancy colored stones- the most desirable fancy colored diamonds in the world are cut this way.

Maybe there is something about this look we can classify as desirable?
Anything?

David,
when we finish discussion about Fire, Colorless Crushed Ice cuts, I am happy discuss Fancy Color diamonds.

where is your Fire definition ? what is Fire in diamond for you?

 

[Serg]

David,

re:But sometimes 1000 greens is as desirable than 8 reds.

I prefer something between. For my taste classical round cut 6 mm has too big VF's, and Crushed Ice cuts 6 mm have too small virtual facets.

if cut has only big VF's then few Fire flashes come per second( in Consumer light environment)( but if consumer has not sharp vision he needs cut with even bigger VF's, for example Emerald. Better to see Fire Flashes rarely , then do not see any Fire flashes)

If Cut has many VF's( as Crushed Ice cut) then all flashes are too small to enjoy Colorfull flashes.

there is possibility for mixed "50 greens ,100 reds, 20 blues" in same Cushion cut. it has much better balance between Fire and Brilliancy than Crushed Ice cuts. there is not special name for such Type cuts yet.

 

[RandG]

A friend just pointed me to this extremely interesting thread so I figured I'd chime in with my 2 cents. I fully agree with David, and I think with everyone else here that with fancy shapes there is no substitute for seeing the diamond. ASET scans provide valuable data that, if interpreted correctly by an expert, can ( when considered together with other data like a Sarin report and a photo), give an expert a a pretty good idea of what the diamond might look like if he/she got to see it. it is, however, even to the expert who knows how to interpret the data, no substitute fore the human eye which provides the best data of all and ultimately the only data that matters.

I also agree with David that the "red is better" mantra is a misleading oversimplification. Too much red around the culet of a radiant cut ASET scan is an indication that there will be a concentration of black around the culet, a sign of a poorly cut diamond that has the facets forming the culet on too high an angle. I recut such diamonds all the time likely resulting in a much more attractive radiant but very possibly with an ASET scan that some commentators here might consider less desirable because it has less of a concentration of red.

It should also be remembered that the entire concept of the ASET is based on the idea that the most important light is the light that comes toward the diamond from above. That is certainly true when the ring is on your finger and you are holding it up to admire it yourself. But when the diamond is actually being worn and your arms are moving around, the diamond spends relatively little time with the table pointed to the sky. Most of the time the overhead light will actually be oriented toward the side of the diamond not the top.

As a tool for consumers the ASET is, in my opinion, of limited value with respect to fancy shapes because consumers (and frankly some of those who provide advice to others on this site) simply do not have the expertise to properly interpret the scan and that expertise cannot be gained simply by reviewing a few sample princess cut ASETs shown as examples. You certainly can't extrapolate from a princess to a radiant because the cuts are intended to reflect light differently. Relying on a misinterpretation of data is worse than not having the data at all and even well meaning "experts" without alternate agendas too often provide incorrect or over simplified interpretations simply because they are not as "expert" as they think they are.

The best substitute for your own eyes, if you are buying sight unseen, is buying from someone you trust, trusting their eyes as a substitute for your own.

Excellent post! I sometimes see novice consumers coming to this forum, dissuaded by "experts" from beautiful fancy cut stones because the vendor does not offer an ASET, the ASET/specs do not meet some arbitrary standard of "ideal" or because there is an assumption based on a few photos that a stone does not merit further review only to then be pushed to vendors who offer ASET images, to the exclusion of those who don't. This is my only objection to the extensive marketing of ASET use on this site. It's a tool, not the exclusive basis in which to choose a fancy cut diamond. Cut is important, but no more than any other factor used to judge a stone, with your eyes being the best judge. Modern day "ideal" standards are not for everyone, nor should they be held out as the benchmark for successful diamond buying. I wouldn't own a single stone if they did!

RandG, as one who sells ASET, and someone with a lot of experiance using it and ideal-scope to buy diamonds, it is a rejection tool. If a vendor refuses to supply ASET images it is very often the case that the stones would and should be rejected based on the ASET and its interpretaions here on PS. However that said, there are examples where some consumers give the wrong advice - no doubt. Its something that I ask all people to bring to mine and other experianced posters attention so we can intercede and help educate the prosumers.

I'm not so sure consumer worthy vendors not promoted on the site "refuse" to provide ASET images, as much as they haven't bought into the technology and they simply don't view ASET as a basis by which to exclude a stone, exclusively, and particularly for anything but a modern round.

However, if it's your sales and marketing strategy to use Prosumers/Consumers to promote the wider use of ASET images as a "tool for elimination", the site is doing a great job! All you have to do is follow a few days worth of posts to appreciate how much.

 

[Texas Leaguer]

A friend just pointed me to this extremely interesting thread so I figured I'd chime in with my 2 cents. I fully agree with David, and I think with everyone else here that with fancy shapes there is no substitute for seeing the diamond. ASET scans provide valuable data that, if interpreted correctly by an expert, can ( when considered together with other data like a Sarin report and a photo), give an expert a a pretty good idea of what the diamond might look like if he/she got to see it. it is, however, even to the expert who knows how to interpret the data, no substitute fore the human eye which provides the best data of all and ultimately the only data that matters.

I also agree with David that the "red is better" mantra is a misleading oversimplification. Too much red around the culet of a radiant cut ASET scan is an indication that there will be a concentration of black around the culet, a sign of a poorly cut diamond that has the facets forming the culet on too high an angle. I recut such diamonds all the time likely resulting in a much more attractive radiant but very possibly with an ASET scan that some commentators here might consider less desirable because it has less of a concentration of red.

It should also be remembered that the entire concept of the ASET is based on the idea that the most important light is the light that comes toward the diamond from above. That is certainly true when the ring is on your finger and you are holding it up to admire it yourself. But when the diamond is actually being worn and your arms are moving around, the diamond spends relatively little time with the table pointed to the sky. Most of the time the overhead light will actually be oriented toward the side of the diamond not the top.

As a tool for consumers the ASET is, in my opinion, of limited value with respect to fancy shapes because consumers (and frankly some of those who provide advice to others on this site) simply do not have the expertise to properly interpret the scan and that expertise cannot be gained simply by reviewing a few sample princess cut ASETs shown as examples. You certainly can't extrapolate from a princess to a radiant because the cuts are intended to reflect light differently. Relying on a misinterpretation of data is worse than not having the data at all and even well meaning "experts" without alternate agendas too often provide incorrect or over simplified interpretations simply because they are not as "expert" as they think they are.

The best substitute for your own eyes, if you are buying sight unseen, is buying from someone you trust, trusting their eyes as a substitute for your own.

Excellent post! I sometimes see novice consumers coming to this forum, dissuaded by "experts" from beautiful fancy cut stones because the vendor does not offer an ASET, the ASET/specs do not meet some arbitrary standard of "ideal" or because there is an assumption based on a few photos that a stone does not merit further review only to then be pushed to vendors who offer ASET images, to the exclusion of those who don't. This is my only objection to the extensive marketing of ASET use on this site. It's a tool, not the exclusive basis in which to choose a fancy cut diamond. Cut is important, but no more than any other factor used to judge a stone, with your eyes being the best judge. Modern day "ideal" standards are not for everyone, nor should they be held out as the benchmark for successful diamond buying. I wouldn't own a single stone if they did!

RandG, as one who sells ASET, and someone with a lot of experiance using it and ideal-scope to buy diamonds, it is a rejection tool. If a vendor refuses to supply ASET images it is very often the case that the stones would and should be rejected based on the ASET and its interpretaions here on PS. However that said, there are examples where some consumers give the wrong advice - no doubt. Its something that I ask all people to bring to mine and other experianced posters attention so we can intercede and help educate the prosumers.

I'm not so sure consumer worthy vendors not promoted on the site "refuse" to provide ASET images, as much as they haven't bought into the technology and they simply don't view ASET as a basis by which to exclude a stone, exclusively, and particularly for anything but a modern round.

However, if it's your sales and marketing strategy to use Prosumers/Consumers to promote the wider use of ASET images as a "tool for elimination", the site is doing a great job! All you have to do is follow a few days worth of posts to appreciate how much.

RandG,
I can understand how you might get those impressions. However, the growth of the use of ASET and other diagnostic tools has been organic within this community. It is true that diamonds are generally not dissected in the broader jewelry community the way they are here. To a great extent the traditional jewelry industry is lagging behind in terms of understanding cut quality. Consumers come here looking for more information than they are getting elsewhere.

This forum was quite active well before AGS launched their light performance cut grading system of which the ASET tool is fundamental. The new system was a true game changer. The scientifically vetted research that had been going on in the background for years using ray tracing technologies finally resulted in a system for evaluating a 3D model of a diamond and calculating the contribution of every facet to overall light performance. Naturally forum members were keen to learn about this newsystem and it's graphical tool ASET. It was another excellent way to be able to discuss different aspects of remote diamonds on the internet, in combination with other pieces of information, in order to gain better overall understanding of a diamond's potential for beauty.

I don't think that the fact that most B&M stores don't use ASET is that they haven't bought into it in the sense that they don't believe in its value. Most have simply not learned about it. Those that do keep up with advances in gemology are going to have a competitive edge over their competition as consumers are becoming more and more educated and are challenging their merchants to provide high level products, services and information.

Having said all that, there certainly are differences in the ASET signatures of different shapes and facet arrangements. We do need to learn more about those differences so that consumers get the best advice here. And as always, especially with fancies, the human eye is the final arbiter of beauty. The tools are valuable for determining which diamonds to focus those eyes on.

 

[Rockdiamond]

Serg- please have a look at the top sellers in the world of Fancy Colored Diamonds.
Please notice how the most sought after fancy yellow radiant or cushion cut diamonds are cut ( crushed ice)
Please notice how these diamonds are set- in many cases the pavilion is obstructed by parts of the ring- and many times on purpose.
Look at the resulting rings.
Maybe you find this type of look to be sub-standard.
Maybe the people you showed your test felt the same way.
But Harry Winston,Tiffany, Graff, and many others are finding far different results in the real world.
The look we're calling "Crushed ice" has found wide acceptance - even if the pavilion is obstructed.
The finest fancy colored stones- the most desirable fancy colored diamonds in the world are cut this way.

Maybe there is something about this look we can classify as desirable?
Anything?

David,
when we finish discussion about Fire, Colorless Crushed Ice cuts, I am happy discuss Fancy Color diamonds.

where is your Fire definition ? what is Fire in diamond for you?

Hi Serg,
Thank you for responding.
I am constantly doing tests on diamonds- and appreciate the method you suggested.
In general I find the most important test is actually setting the diamond to see how it's light performance is affected.

My definition of fire:
To answer simply, what I see as fire in a diamond is the way it reflects the light back to my eye.
The ASET definitely can detect differences in the brilliance of the reflections, yet sometimes my eye is pleased more by reflections that ASET proves are less brilliant - such as the facets showing green in ASET.
So, if we say a round brilliant has more "fire" than a well cut radiant, we'd have to define fire better IMO

 

[Texas Leaguer]

Serg- please have a look at the top sellers in the world of Fancy Colored Diamonds.
Please notice how the most sought after fancy yellow radiant or cushion cut diamonds are cut ( crushed ice)
Please notice how these diamonds are set- in many cases the pavilion is obstructed by parts of the ring- and many times on purpose.
Look at the resulting rings.
Maybe you find this type of look to be sub-standard.
Maybe the people you showed your test felt the same way.
But Harry Winston,Tiffany, Graff, and many others are finding far different results in the real world.
The look we're calling "Crushed ice" has found wide acceptance - even if the pavilion is obstructed.
The finest fancy colored stones- the most desirable fancy colored diamonds in the world are cut this way.

Maybe there is something about this look we can classify as desirable?
Anything?

David,
when we finish discussion about Fire, Colorless Crushed Ice cuts, I am happy discuss Fancy Color diamonds.

where is your Fire definition ? what is Fire in diamond for you?

Hi Serg,
Thank you for responding.
I am constantly doing tests on diamonds- and appreciate the method you suggested.
In general I find the most important test is actually setting the diamond to see how it's light performance is affected.

My definition of fire:
To answer simply, what I see as fire in a diamond is the way it reflects the light back to my eye.
The ASET definitely can detect differences in the brilliance of the reflections, yet sometimes my eye is pleased more by reflections that ASET proves are less brilliant - such as the facets showing green in ASET.
So, if we say a round brilliant has more "fire" than a well cut radiant, we'd have to define fire better IMO

David,
Again, I don't want to speak for Serg, but I think we may have stumbled across a source of the problem in communication. Most in the industry understand "fire" to be associated with dispersion and the resulting individual colored flashes that diamonds can produce. ASET does not directly inform us of fire.

Here is the article describing science and methodology behind the AGS light performance system. See Gem Fire section 5.4
http://www.agslab.com/spie/spie_lo_res.pdf

 

[Rockdiamond]

Thank you Bryan!
You are correct, I needed to read that.
Got it.
Fire.
It does make it a lot easier to communicate if we understand the terminology.

 

[beryl]

If the stone looks pretty to your eyes, that's what counts. Stereo vision is the real thing.
By the way, Harding's article about obstruction was in GIA's 'Gems & Gemology', Fall 1975.

 

[Garry H (Cut Nut)]

If the stone looks pretty to your eyes, that's what counts. Stereo vision is the real thing.
By the way, Harding's article about obstruction was in GIA's 'Gems & Gemology', Fall 1975.

Sorry Bruce - here is the link http://www.gemology.ru/cut/english/faceting/
And here is an image from the Cut Group's recent articles (Bruce / Beryl has helped with some editing).