Light leakage, how can you tell in real life?

[Texas Leaguer]

It is a pretty well established fact that people find diamonds beautiful. There are various aspects to that beauty. The whole purpose of researching light performance is to understand what the components of beauty are, how they might be quantified, how they relate to one another and to human sensory systems, and what the implications are for cut craftsmanship. To the extent that consumers understand these things they can make better purchasing decisions. To the extent diamond cutters can better understand these things, they can cut more beautiful diamonds (yes I said beautiful). And to the extent we merchants understand it better, we can offer better products and guidance to our customers.

Well said! I would add.
And diamond designers can create better designs and be more sure of a design before it is actually cut.
There is a lot of "that looks right" that goes into diamond design today.
Replacing at least some of that with scientific data improves how diamonds are designed and reduces the risks of cutting expensive rough into a new design.
I think "that looks right" will always be a part of it however.

Agreed. It will always be a combination of science and art. Developing the science will enable the artists more freedom of expression, and consumers more excellent choices.

 

[Garry H (Cut Nut)]

David without your moronic statements we would probably not have many of these discussions. So actually it will be a sad day if you ever stop asking stupid questions and making dopey comments.
Keep it up please.
But it is good that you are advancing - you are now able to understand and see what you did not 4 years ago

Now back to Sergey's question - about fire? And about what happens when there is no backlight on a pinfire crushed ice diamond?

 

[Rockdiamond]

Thank you Gary we are agree. If you stop publishing misleading charts I'll stop asking questions…
Regarding your question which is a very good one, and central to the discussion:
Without a doubt a pinfire crushed ice cushion definitely benefits from light coming in through the back.
But obviously it does not go completely dark without it.
I drew a comparison between fancy colored diamonds and colorless pinfire cushions earlier in the thread. Of course there are differences, but there's a lot of similarities as well, wouldn't you agree?
It's a question of degree… Painting the facets on the pavilion at a fancy colored diamond reduces contrast.
Although the facets on the pavilion of most colorless crushed ice cushions are dugout as opposed to painted, in many cases the results produced in scintillation are similar.
That is to say: although it's not nearly as bright as when you put light behind it, there is a certain sparkle people find attractive. There – I have used an unscientific word

 

[Rockdiamond]

Constructive suggestion:
Replace Excellent with:
An ASET similar to this will likely produce large bright flashes. Such a stone will likely show contrast, which is considered very attractive to many observers. In some of cases, such a stone may show fire, considered very desirable- although not guaranteed based on ASET. In many cases, stones cut for maximum contrast and fire will not have the surface are of well cut "pinfire" stones. It may also be necessary to polish away more of the rough diamond to achieve these results, resulting in a higher per carat price versus "pinfire" stones.


Replace Fair with:
If you want a nicely cut, yet slightly "spready" Cushion Princess or Radiant, it will likely have a lot of green in the aset.
An ASET similar to this may be a "pinfire" performance stone. It will have many more flashes, although each will be significantly less bright as compared to a well cut stone which was cut for high contract brightest flashes. Additionally, such stones will be unlikely to produce significant fire. Red mixed with the green may indicate areas of contrast- which may or may not be desirable. It is also extremely important to take care to keep the pavilion of the stone clean, as dirt on the pavilion greatly affects performance. In the best cases, such stones may have larger surface area for their weight than stones cut for the brighter flashes. Since cutters can get a better yield from such designs, such stones may be priced below the type of stone described above, on a per carat basis.

Total generalizations- but the point is, have labels suggesting potential of each type of cut more holistically.

 

[kenny]

David without your moronic statements we would probably not have many of these discussions.
So actually it will be a sad day if you ever stop asking stupid questions and making dopey comments.
Keep it up please.

IMO it stands to reason that a diamond vendor spending years attacking the very idea of good cut, and tools to identify it, must sell many poorly cut diamonds.

America has a huge population that is anti-science, anti-education, and anti-smarts.
All that matters is you love it and it makes your heart sing , is non-advice I read often on PS.
Perhaps this is the target demographic of such a vendor.

Oh well, people vary.

 

[CanuckAB]

+1

 

[Rockdiamond]

Thanks for the endorsement Kenny.
In spite of your signature, you don't seem to vary all that much
In fact, this whole thread is about leakage- and the science of ASET. That is, how to properly balance the information it's giving us.
There's quite a bit of science in cutting a well cut crushed ice (pinfire) diamond. As well as art.
Fortunately many of the cutters have gotten better and better at cutting this type of stone. I love that science, yes.

It's also clear form this, and other discussions that it's far easier defining what is well cut if a stone is cut specifically for light performance-
Part of what you're saying is true, a great deal of the many thousands of stones we sell each year are NOT cut for light performance, as they are fancy colored diamonds.
But it does give me quite a bit of knowledge in selecting Pinfire cushions and radiant cuts- as well as tremendous experience in what buyers ( many of them PS reader) love.

 

[Garry H (Cut Nut)]

Constructive suggestion:
Replace Excellent with:
An ASET similar to this will likely produce large bright flashes. Such a stone will likely show contrast, which is considered very attractive to many observers. In some of cases, such a stone may show fire, considered very desirable- although not guaranteed based on ASET. In many cases, stones cut for maximum contrast and fire will not have the surface are of well cut "pinfire" stones. It may also be necessary to polish away more of the rough diamond to achieve these results, resulting in a higher per carat price versus "pinfire" stones.


Replace Fair with:
If you want a nicely cut, yet slightly "spready" Cushion Princess or Radiant, it will likely have a lot of green in the aset.
An ASET similar to this may be a "pinfire" performance stone. It will have many more flashes, although each will be significantly less bright as compared to a well cut stone which was cut for high contract brightest flashes. Additionally, such stones will be unlikely to produce significant fire. Red mixed with the green may indicate areas of contrast- which may or may not be desirable. It is also extremely important to take care to keep the pavilion of the stone clean, as dirt on the pavilion greatly affects performance. In the best cases, such stones may have larger surface area for their weight than stones cut for the brighter flashes. Since cutters can get a better yield from such designs, such stones may be priced below the type of stone described above, on a per carat basis.

Total generalizations- but the point is, have labels suggesting potential of each type of cut more holistically.

David you still have not answered Sergey's question about FIRE.
Re the Ex Princess cut - if this is a 1ct stone (which is about what it was - but I made that chart close to 10 years ago) then I promise you it had very little fire.
Secondly, how did you ever get the idea that the 'fair' stone would be spready - that would not have been the case at all.
Thirdly, even if such a stone was 10% smaller for the same weight, a diamond like the Ex one will appear larger in most lighting.
Any idea why?

 

[Rockdiamond]

Garry- are you speaking of this question, page 2?

Dave,
1) what is Fire for you?
your Comments about Fire looks very strange for me. Please Clarify you Fire definition

I have read the part of the paper where the phenomena is described-
I take it to mean the prism's that come off the diamond when the angular subtend between the pupil, light source and facet plane are properly aligned- is that correct?

Secondly, how did you ever get the idea that the 'fair' stone would be spready - that would not have been the case at all.

I have seen stones that were spready have similar ASET signatures. I didn't say "would" I said "could"

Thirdly, even if such a stone was 10% smaller for the same weight, a diamond like the Ex one will appear larger in most lighting.
Any idea why?

Part of what I have been doing for this discussion is spending time speaking to a few diamond cutters to further refine my understanding.
I have an idea the scientific observations you will point to to back up your statement- however I feel that there's too many variables on the non LP stones we would use to compare.
And why do you assume only 10%?
The difference could be far greater.

 

[RADIANTMAN]

When I originally posted here, I had not actually read the post that started the discussion. Now that I have I have to admit to being astonished. The original poster had purchased a diamond she (I'm guessing at the gender) loved, but became concerned about her diamond not because her eyes picked up something that concerned her but because she read something on here about leakage after the purchase had been made and the ring was on her finger.

She was advised to get an ASET to find out if something was indeed wrong with her diamond (even though it looked beautiful to her. In my opinion this entire discussion is exhibit A of the problems created because of the misunderstanding of what our "science" actual tells us and what it does not. The ASET, in this instance was not proposed as a means to help rule out likely bad diamonds in order to make the buying process more efficient. It was proposed as a better judge of the poster's diamond (that she had already purchased}, than her own sense of beauty.

Data is objective - the interpretation of data is not. It is nevertheless often presented as if it is.

Many years ago, I was approached at a trade by a vendor of a well known (and now very successful) diamond technology company (that will remain nameless here) asking me if I would consider using their technology as part of my brand. They assured me that their cut grading process worked for all shapes, including radiants. I responded that if it worked I'd be happy, even excited, to incorporate it into my marketing, though radiants are more complicated to evaluate than rounds so I did not believe that technology designed around evaluating rounds was likely to work well for radiants without some significant amount of additional research and adjustment that I was doubtful that they had done since it would be time consuming and costly to do.

I took a few of my ideal cut radiants and borrowed a few poorly cut ones from other exhibitors and had them rank them. The machine graded the ugly radiants higher than the nice ones. It was suggested to me that the "science" was correct - it was science after all and therefore indisputable. The problem, according to the folks who developed the technology, was that my perception of beauty was wrong and needed to change.

I can tell you that expert eyes were not needed to rank these diamonds properly and 100 uneducated or educated consumers would all have ranked them more or less the same way I did. The owners of the ugly diamonds also thought there diamonds were ugly - I had asked them to lend me some stinkers not their beauties. Nobody would have chosen the monstrosity the machine liked as the nicest diamond. The data gathered by the machine was, I'm sure, completely accurate but it may not have been the correct data needed to evaluate radiants or the data may simply have been interpreted incorrectly if the goal was to evaluate the beauty of the diamond that was not round.

Conceptions about what is "good" or "bad" in an ASET scan were developed based on the ideal appearance of round brilliants. When the same conceptions were applied to fancies it quickly became clear that those conceptions needed to be adjusted for each shape if they were to have any serious relationship to human perceptions of beauty. This fact has been misconstrued by some as meaning that fancies simply cannot be as beautiful as rounds so we need to "accept" "deficiencies" such as leakage. But if a fancy could actually achieve the ASET image of a well cut round it would be a gorgeous diamond. In reality, for radiants at least, the ideal ASET (at least for the radiant that I consider ideal) looks nothing like the ideal ASET for a round and radiants with ASETs that approach that of a round look like crap.

Each shape has a proper range of patterning for that shape. To the extent princess patterning is used to evaluate radiants or cushions that is, in my opinion, as incorrect as attempting to apply round patterning. Modified cushions and radiants are similar enough to be evaluated similarly but emeralds and princesses and cushion brilliants are quite different. Yet well meaning advice is often given based on a few princess samples that Garry has provided and it is often said that radiants are somehow not beautiful or brilliant diamonds because they don't yield a particular ASET image.

Perhaps the solution would be to update the information on this site with ASET imagery for more shapes, showing different images for each shape not as better or worse but to reflect how the images change as you shift the subjective compromises that reflect individual tastes. Using images of truly badly cut diamonds of each shape would be a useful tool to help rule out the stinkers. But presenting legitimate choices reflecting individual taste as somehow involving compromise from a supposedly "ideal" ASET image is, in my opinion, misleading and not helpful to consumers.

I always present my brand as providing choices within which the customer cannot make a mistake. But within that range the customer must make choices reflecting their own preferences - even my father and I often did not agree on which radiant we liked the best. When the ASET is presented that way it can be an excellent weeding out tool. Unfortunately a quick scan of posts here (admittedly not an exhaustive sampling) reveals that this is not always the case and that is where my concern lies.

 

[Garry H (Cut Nut)]

When I originally posted here, I had not actually read the post that started the discussion. Now that I have I have to admit to being astonished. The original poster had purchased a diamond she (I'm guessing at the gender) loved, but became concerned about her diamond not because her eyes picked up something that concerned her but because she read something on here about leakage after the purchase had been made and the ring was on her finger.

She was advised to get an ASET to find out if something was indeed wrong with her diamond (even though it looked beautiful to her. In my opinion this entire discussion is exhibit A of the problems created because of the misunderstanding of what our "science" actual tells us and what it does not. The ASET, in this instance was not proposed as a means to help rule out likely bad diamonds in order to make the buying process more efficient. It was proposed as a better judge of the poster's diamond (that she had already purchased}, than her own sense of beauty.

Data is objective - the interpretation of data is not. It is nevertheless often presented as if it is.

Many years ago, I was approached at a trade by a vendor of a well known (and now very successful) diamond technology company (that will remain nameless here) asking me if I would consider using their technology as part of my brand. They assured me that their cut grading process worked for all shapes, including radiants. I responded that if it worked I'd be happy, even excited, to incorporate it into my marketing, though radiants are more complicated to evaluate than rounds so I did not believe that technology designed around evaluating rounds was likely to work well for radiants without some significant amount of additional research and adjustment that I was doubtful that they had done since it would be time consuming and costly to do.

I took a few of my ideal cut radiants and borrowed a few poorly cut ones from other exhibitors and had them rank them. The machine graded the ugly radiants higher than the nice ones. It was suggested to me that the "science" was correct - it was science after all and therefore indisputable. The problem, according to the folks who developed the technology, was that my perception of beauty was wrong and needed to change.

I can tell you that expert eyes were not needed to rank these diamonds properly and 100 uneducated or educated consumers would all have ranked them more or less the same way I did. The owners of the ugly diamonds also thought there diamonds were ugly - I had asked them to lend me some stinkers not their beauties. Nobody would have chosen the monstrosity the machine liked as the nicest diamond. The data gathered by the machine was, I'm sure, completely accurate but it may not have been the correct data needed to evaluate radiants or the data may simply have been interpreted incorrectly if the goal was to evaluate the beauty of the diamond that was not round.

Conceptions about what is "good" or "bad" in an ASET scan were developed based on the ideal appearance of round brilliants. When the same conceptions were applied to fancies it quickly became clear that those conceptions needed to be adjusted for each shape if they were to have any serious relationship to human perceptions of beauty. This fact has been misconstrued by some as meaning that fancies simply cannot be as beautiful as rounds so we need to "accept" "deficiencies" such as leakage. But if a fancy could actually achieve the ASET image of a well cut round it would be a gorgeous diamond. In reality, for radiants at least, the ideal ASET (at least for the radiant that I consider ideal) looks nothing like the ideal ASET for a round and radiants with ASETs that approach that of a round look like crap.

Each shape has a proper range of patterning for that shape. To the extent princess patterning is used to evaluate radiants or cushions that is, in my opinion, as incorrect as attempting to apply round patterning. Modified cushions and radiants are similar enough to be evaluated similarly but emeralds and princesses and cushion brilliants are quite different. Yet well meaning advice is often given based on a few princess samples that Garry has provided and it is often said that radiants are somehow not beautiful or brilliant diamonds because they don't yield a particular ASET image.

Perhaps the solution would be to update the information on this site with ASET imagery for more shapes, showing different images for each shape not as better or worse but to reflect how the images change as you shift the subjective compromises that reflect individual tastes. Using images of truly badly cut diamonds of each shape would be a useful tool to help rule out the stinkers. But presenting legitimate choices reflecting individual taste as somehow involving compromise from a supposedly "ideal" ASET image is, in my opinion, misleading and not helpful to consumers.

I always present my brand as providing choices within which the customer cannot make a mistake. But within that range the customer must make choices reflecting their own preferences - even my father and I often did not agree on which radiant we liked the best. When the ASET is presented that way it can be an excellent weeding out tool. Unfortunately a quick scan of posts here (admittedly not an exhaustive sampling) reveals that this is not always the case and that is where my concern lies.

The Cut Group, with who I work, frequently refer to your Father, Mr Grossbard's development of one of only two effective new cut designs since Tolkowsky narrowed the range for round brilliants.
I definitely do not wish to reduce the number of identifiable appearance and patterns in diamonds.
I highlighted the part where you refer to the ASET being developed for round diamonds. If that is true or not, it is not a tool that I recommend to either identify leakage or look at rounds with. It is too complex.
But as you rightly state - fancy shapes are more complex that rounds and so a more complex reflector structured lighting is more helpful.
ASET is one of the tools the Cut group uses (along with many other) to develop more beautiful cuts - the current project - cushion cuts -is led by the OctoNus group, with sample stones being polished in the LTM factory in Surat. I have acquired a parcel those stones which I am debating how to market and sell - they do indeed rival round brilliant cuts, and in many cases the brilliance is very close to as good as the best rounds, and often they show more fire.
Below are 4 ASET images (so far there are about 10 variants in the evolution of the Cushion cuts - so the patterns are not identical). The aim is to rival or outperform the best round cuts in one or more aspects of beauty. Those who have seen these stones are impressed, and they stand up well in side by side comparisons with round diamonds.

It would be interesting to study radiants too. Would you be interested to participate?

 

[teobdl]

Thank you, RadiantMan. Your post should be requisite reading.

 

[Texas Leaguer]

When I originally posted here, I had not actually read the post that started the discussion. Now that I have I have to admit to being astonished. The original poster had purchased a diamond she (I'm guessing at the gender) loved, but became concerned about her diamond not because her eyes picked up something that concerned her but because she read something on here about leakage after the purchase had been made and the ring was on her finger.

She was advised to get an ASET to find out if something was indeed wrong with her diamond (even though it looked beautiful to her. In my opinion this entire discussion is exhibit A of the problems created because of the misunderstanding of what our "science" actual tells us and what it does not. The ASET, in this instance was not proposed as a means to help rule out likely bad diamonds in order to make the buying process more efficient. It was proposed as a better judge of the poster's diamond (that she had already purchased}, than her own sense of beauty.

Data is objective - the interpretation of data is not. It is nevertheless often presented as if it is.

Many years ago, I was approached at a trade by a vendor of a well known (and now very successful) diamond technology company (that will remain nameless here) asking me if I would consider using their technology as part of my brand. They assured me that their cut grading process worked for all shapes, including radiants. I responded that if it worked I'd be happy, even excited, to incorporate it into my marketing, though radiants are more complicated to evaluate than rounds so I did not believe that technology designed around evaluating rounds was likely to work well for radiants without some significant amount of additional research and adjustment that I was doubtful that they had done since it would be time consuming and costly to do.

I took a few of my ideal cut radiants and borrowed a few poorly cut ones from other exhibitors and had them rank them. The machine graded the ugly radiants higher than the nice ones. It was suggested to me that the "science" was correct - it was science after all and therefore indisputable. The problem, according to the folks who developed the technology, was that my perception of beauty was wrong and needed to change.

I can tell you that expert eyes were not needed to rank these diamonds properly and 100 uneducated or educated consumers would all have ranked them more or less the same way I did. The owners of the ugly diamonds also thought there diamonds were ugly - I had asked them to lend me some stinkers not their beauties. Nobody would have chosen the monstrosity the machine liked as the nicest diamond. The data gathered by the machine was, I'm sure, completely accurate but it may not have been the correct data needed to evaluate radiants or the data may simply have been interpreted incorrectly if the goal was to evaluate the beauty of the diamond that was not round.

Conceptions about what is "good" or "bad" in an ASET scan were developed based on the ideal appearance of round brilliants. When the same conceptions were applied to fancies it quickly became clear that those conceptions needed to be adjusted for each shape if they were to have any serious relationship to human perceptions of beauty. This fact has been misconstrued by some as meaning that fancies simply cannot be as beautiful as rounds so we need to "accept" "deficiencies" such as leakage. But if a fancy could actually achieve the ASET image of a well cut round it would be a gorgeous diamond. In reality, for radiants at least, the ideal ASET (at least for the radiant that I consider ideal) looks nothing like the ideal ASET for a round and radiants with ASETs that approach that of a round look like crap.

Each shape has a proper range of patterning for that shape. To the extent princess patterning is used to evaluate radiants or cushions that is, in my opinion, as incorrect as attempting to apply round patterning. Modified cushions and radiants are similar enough to be evaluated similarly but emeralds and princesses and cushion brilliants are quite different. Yet well meaning advice is often given based on a few princess samples that Garry has provided and it is often said that radiants are somehow not beautiful or brilliant diamonds because they don't yield a particular ASET image.

Perhaps the solution would be to update the information on this site with ASET imagery for more shapes, showing different images for each shape not as better or worse but to reflect how the images change as you shift the subjective compromises that reflect individual tastes. Using images of truly badly cut diamonds of each shape would be a useful tool to help rule out the stinkers. But presenting legitimate choices reflecting individual taste as somehow involving compromise from a supposedly "ideal" ASET image is, in my opinion, misleading and not helpful to consumers.

I always present my brand as providing choices within which the customer cannot make a mistake. But within that range the customer must make choices reflecting their own preferences - even my father and I often did not agree on which radiant we liked the best. When the ASET is presented that way it can be an excellent weeding out tool. Unfortunately a quick scan of posts here (admittedly not an exhaustive sampling) reveals that this is not always the case and that is where my concern lies.

Stan,
Thanks for taking the time to make an excellent post. You are a top expert in the field and I think the forum would be well served to get your take on the unique attributes of radiant cuts, and how to interpret various pieces of information about them, including their ASET signatures.

I think if you follow conversations here more frequently you will find that most people recognize that fancy cuts in general dance to a different tunes than rounds. Because fancies are more complicated I think there is a need for more expertise in interpreting available information. I think the first thing that has to be recognized is the nature of the discussions here are about remote diamonds. Therefore it is necessary to assemble useful pieces of information, interpret them properly, and put together a picture of the diamond being considered.

As you might have picked up from this thread, despite some of the detours, there is recognition that the beauty aspects of diamonds involve more than what part of the angular spectrum the diamond is drawing light from. When you study subject in depth you start getting into human perception and the amazing workings of the brain. So, most of us are taking this journey with an open mind.

And I think your participation here would be very valuable in developing the proper understanding of fancy cuts.

 

[Texas Leaguer]

Below are 4 ASET images (so far there are about 10 variants in the evolution of the Cushion cuts - so the patterns are not identical). The aim is to rival or outperform the best round cuts in one or more aspects of beauty. Those who have seen these stones are impressed, and they stand up well in side by side comparisons with round diamonds.

Garry,
Those do indeed look like they would be beautiful cushions.

 

[Rockdiamond]

Yes, thank you Stan!
I am proud to say that from the beginning of my involvement here on PS, at least 10 years back, Stan is one of the cutters that has taught me a the most about asset and it's relationship to well cut colorless radiant diamonds. Since we get the chance to look at a lot of the same stones it's real world learning.
I will be honest in that I have encouraged Stan to look at the discussions of Radiant diamonds here as I believe his expert opinion adds tremendous context.
No question he can more eloquently express some of the things I've been pointing out all along.
Great post Stan

 

[Karl_K]

Below are 4 ASET images (so far there are about 10 variants in the evolution of the Cushion cuts - so the patterns are not identical). The aim is to rival or outperform the best round cuts in one or more aspects of beauty. Those who have seen these stones are impressed, and they stand up well in side by side comparisons with round diamonds.

Garry,
Those do indeed look like they would be beautiful cushions.

I would say it as:
They look like they have the potential to be beautiful cushions.

Which actually brings us back to this discussion.
Radiantman and David if you disagree with how ASET is applied to radiants then would it not be a good thing to show us what to look for in ASET even if it is only your opinion or some evidence of what works and what don't with ASET and radiants?
Saying your wrong is not going to help people.

 

[Rockdiamond]

Karl, a big part of the "heated" debate involves what you're calling "evidence"- although you did use the word opinion as well, thank you.
When I first read about the scientific analysis of light return I was beyond skeptical- and of course this was many years ago.
Leakage?
I understood how you can see through a poorly cut, shallow diamond- but how does that relate to a well cut radiant?
The word itself has connotations, and they are negative.
What this points out is that scientific measurements, as opposed to the analysis of these measurements are two totally different things.
Yet when I have pointed this out, and for many years, I get branded as someone who hates well cut diamonds.
I was called ( among other things) a Luddite.
I was accused of arguing against science- which 10 years ago, I was.
But I've learned a lot.
Leakage is not "bad"
Light Return is not "good"
Both exist, and can be documented with reflectors- but applying labels that imply value is misleading.

Stan and I will not agree on every aspect of what defines a well cut radiant. But we will be able to agree on a lot of it.

In terms of helping people, I agree- just saying- "this is wrong" does not help anyone.
Nor does it help to have people educated ( indoctrinated) using analysis of scientific observations which is based on subjective evaluations.
Then you get tradespeople using terms like "Red is preferable".
No matter what follows that statement, the meaning is clear. Anything else ( like green) is less than preferable. Leading to a lot of well meaning consumers repeating this mantra.

Make no mistake, there's a tremendous amount of valuable consumer data here on PS- but ASET interpretation - as well as understanding leakage in well cut diamonds is surely lacking.

 

[Karl_K]

I understood how you can see through a poorly cut, shallow diamond- but how does that relate to a well cut radiant?
Actually what is called commonly called leakage is areas of the diamond drawing light from the pavilion. Not leakage like a window. Consumers get it but do you? Shallow has little to due with it. Steep/deep stones are more likely to have it than shallow diamonds. The term leakage is technically incorrect but is in common use for so long it is not going to change.

Leakage is not "bad"
It can be bad, good, or just ok and how much and where is ok is different based on the design
Light Return is not "good"
Without light return what is the point of buying a diamond rather then picking up a rock off the road and putting it in a ring? People like sparkly rocks
Both exist, and can be documented with reflectors- but applying labels that imply value is misleading.
There are acceptable and unacceptable levels of light return and leakage.
Then you get tradespeople using terms like "Red is preferable".

What is funny is I hear that the most from you!

Make no mistake, there's a tremendous amount of valuable consumer data here on PS- but ASET interpretation - as well as understanding leakage in well cut diamonds is surely lacking.

Time and time again you have shown you do not understand "leakage" many consumers get it why can't you? It is frankly embarrassing that you after all this time do not get that simple concept!

 

[Serg]

ASET leakage does not equal to Human Stereo Vision leakage.
If ASET shows leakage it does not proof leakage in Stereo Vision.
It is big ASET weakness .

ASET image is not enough to do decision about Fancy cuts( neither positive nor negative)

 

[Rockdiamond]

I understood how you can see through a poorly cut, shallow diamond- but how does that relate to a well cut radiant?
Actually what is called commonly called leakage is areas of the diamond drawing light from the pavilion. Not leakage like a window. Consumers get it but do you? Shallow has little to due with it. Steep/deep stones are more likely to have it than shallow diamonds. The term leakage is technically incorrect but is in common use for so long it is not going to change.

Leakage is not "bad"
It can be bad, good, or just ok and how much and where is ok is different based on the design
Light Return is not "good"
Without light return what is the point of buying a diamond rather then picking up a rock off the road and putting it in a ring? People like sparkly rocks
Both exist, and can be documented with reflectors- but applying labels that imply value is misleading.
There are acceptable and unacceptable levels of light return and leakage.
Then you get tradespeople using terms like "Red is preferable".

What is funny is I hear that the most from you!

Make no mistake, there's a tremendous amount of valuable consumer data here on PS- but ASET interpretation - as well as understanding leakage in well cut diamonds is surely lacking.

Time and time again you have shown you do not understand "leakage" many consumers get it why can't you? It is frankly embarrassing that you after all this time do not get that simple concept!

Karl- we have an entirely different understanding of diamonds.
I assess hundreds of fancy shaped diamonds in any given week- many are stones we purchase, then sell. Many sold to PS readers. If there were problems, you'd hear about it.
You have designed a really cool cut- kudos. That does not give you the right to determine what "acceptable levels of light return and leakage" are. That does not give you the right to assume what I know, or for that matter, consumers.
Please don't assume that you have a good idea of what consumers "get". IN fact, you don't.

I know this due to my experience dealing with thousands of people. Selling someone a diamond is far more "immediate and personal" than posting on a forum.
We ALL have an interest in the information presented here. Cutters can be very single minded- in fact the best ones are. They believe so much in their product that they might have a harder time impartially assessing stones cut by others.
We have to find ways to better assist consumers in finding out what is the correct balance for THEM- not you Karl.

 

[Rockdiamond]

ASET leakage does not equal to Human Stereo Vision leakage.
If ASET shows leakage it does not proof leakage in Stereo Vision.
It is big ASET weakness .

ASET image is not enough to do decision about Fancy cuts( neither positive nor negative)

Thank you Serg

 

[RADIANTMAN]

"Actually what is called commonly called leakage is areas of the diamond drawing light from the pavilion. Not leakage like a window. Consumers get it but do you? Shallow has little to due with it. Steep/deep stones are more likely to have it than shallow diamonds. The term leakage is technically incorrect but is in common use for so long it is not going to change."

Karl - With all due respect, I do not think that most consumers "get it" that what is commonly called "leakage" is not actually leakage but light drawn from the pavilion, and that is precisely the problem. I think consumers would respond quite differently to being told that a diamond they are considering draws light from the pavilion than to being told that the diamond has a lot of "leakage" and the post that started this thread is a case in point.

I also think you misunderstood David when he said that light return isn't "good." Of course diamonds need a certain amount of light return to be beautiful. I understood him to mean that within a certain range having more light return doesn't necessarily mean that a diamond is more beautiful and I agree fully with that.

At the end of the day, I think we can all agree that the same information can be used to either educate or mislead, and the use of terms like "leakage" (implying bad) and "light return" (implying good) have the potential of sometimes conveying inaccurate impressions disguised as "science." In my opinion, it is our responsibility to make sure we use all of these terms in a manner that helps consumers understand what they actually mean, and how these characteristics actually affect the visual appearance of the diamond (as Serge points out, in stereo.)

 

[RADIANTMAN]

When I originally posted here, I had not actually read the post that started the discussion. Now that I have I have to admit to being astonished. The original poster had purchased a diamond she (I'm guessing at the gender) loved, but became concerned about her diamond not because her eyes picked up something that concerned her but because she read something on here about leakage after the purchase had been made and the ring was on her finger.

She was advised to get an ASET to find out if something was indeed wrong with her diamond (even though it looked beautiful to her. In my opinion this entire discussion is exhibit A of the problems created because of the misunderstanding of what our "science" actual tells us and what it does not. The ASET, in this instance was not proposed as a means to help rule out likely bad diamonds in order to make the buying process more efficient. It was proposed as a better judge of the poster's diamond (that she had already purchased}, than her own sense of beauty.

Data is objective - the interpretation of data is not. It is nevertheless often presented as if it is.

Many years ago, I was approached at a trade by a vendor of a well known (and now very successful) diamond technology company (that will remain nameless here) asking me if I would consider using their technology as part of my brand. They assured me that their cut grading process worked for all shapes, including radiants. I responded that if it worked I'd be happy, even excited, to incorporate it into my marketing, though radiants are more complicated to evaluate than rounds so I did not believe that technology designed around evaluating rounds was likely to work well for radiants without some significant amount of additional research and adjustment that I was doubtful that they had done since it would be time consuming and costly to do.

I took a few of my ideal cut radiants and borrowed a few poorly cut ones from other exhibitors and had them rank them. The machine graded the ugly radiants higher than the nice ones. It was suggested to me that the "science" was correct - it was science after all and therefore indisputable. The problem, according to the folks who developed the technology, was that my perception of beauty was wrong and needed to change.

I can tell you that expert eyes were not needed to rank these diamonds properly and 100 uneducated or educated consumers would all have ranked them more or less the same way I did. The owners of the ugly diamonds also thought there diamonds were ugly - I had asked them to lend me some stinkers not their beauties. Nobody would have chosen the monstrosity the machine liked as the nicest diamond. The data gathered by the machine was, I'm sure, completely accurate but it may not have been the correct data needed to evaluate radiants or the data may simply have been interpreted incorrectly if the goal was to evaluate the beauty of the diamond that was not round.

Conceptions about what is "good" or "bad" in an ASET scan were developed based on the ideal appearance of round brilliants. When the same conceptions were applied to fancies it quickly became clear that those conceptions needed to be adjusted for each shape if they were to have any serious relationship to human perceptions of beauty. This fact has been misconstrued by some as meaning that fancies simply cannot be as beautiful as rounds so we need to "accept" "deficiencies" such as leakage. But if a fancy could actually achieve the ASET image of a well cut round it would be a gorgeous diamond. In reality, for radiants at least, the ideal ASET (at least for the radiant that I consider ideal) looks nothing like the ideal ASET for a round and radiants with ASETs that approach that of a round look like crap.

Each shape has a proper range of patterning for that shape. To the extent princess patterning is used to evaluate radiants or cushions that is, in my opinion, as incorrect as attempting to apply round patterning. Modified cushions and radiants are similar enough to be evaluated similarly but emeralds and princesses and cushion brilliants are quite different. Yet well meaning advice is often given based on a few princess samples that Garry has provided and it is often said that radiants are somehow not beautiful or brilliant diamonds because they don't yield a particular ASET image.

Perhaps the solution would be to update the information on this site with ASET imagery for more shapes, showing different images for each shape not as better or worse but to reflect how the images change as you shift the subjective compromises that reflect individual tastes. Using images of truly badly cut diamonds of each shape would be a useful tool to help rule out the stinkers. But presenting legitimate choices reflecting individual taste as somehow involving compromise from a supposedly "ideal" ASET image is, in my opinion, misleading and not helpful to consumers.

I always present my brand as providing choices within which the customer cannot make a mistake. But within that range the customer must make choices reflecting their own preferences - even my father and I often did not agree on which radiant we liked the best. When the ASET is presented that way it can be an excellent weeding out tool. Unfortunately a quick scan of posts here (admittedly not an exhaustive sampling) reveals that this is not always the case and that is where my concern lies.

The Cut Group, with who I work, frequently refer to your Father, Mr Grossbard's development of one of only two effective new cut designs since Tolkowsky narrowed the range for round brilliants.
I definitely do not wish to reduce the number of identifiable appearance and patterns in diamonds.
I highlighted the part where you refer to the ASET being developed for round diamonds. If that is true or not, it is not a tool that I recommend to either identify leakage or look at rounds with. It is too complex.
But as you rightly state - fancy shapes are more complex that rounds and so a more complex reflector structured lighting is more helpful.
ASET is one of the tools the Cut group uses (along with many other) to develop more beautiful cuts - the current project - cushion cuts -is led by the OctoNus group, with sample stones being polished in the LTM factory in Surat. I have acquired a parcel those stones which I am debating how to market and sell - they do indeed rival round brilliant cuts, and in many cases the brilliance is very close to as good as the best rounds, and often they show more fire.
Below are 4 ASET images (so far there are about 10 variants in the evolution of the Cushion cuts - so the patterns are not identical). The aim is to rival or outperform the best round cuts in one or more aspects of beauty. Those who have seen these stones are impressed, and they stand up well in side by side comparisons with round diamonds.

It would be interesting to study radiants too. Would you be interested to participate?

Garry - i would definitely be interested in learning more about your cut group and what you guys do. Feel free to contact me offline.

 

[Karl_K]

"Actually what is called commonly called leakage is areas of the diamond drawing light from the pavilion. Not leakage like a window. Consumers get it but do you? Shallow has little to due with it. Steep/deep stones are more likely to have it than shallow diamonds. The term leakage is technically incorrect but is in common use for so long it is not going to change."

Karl - With all due respect, I do not think that most consumers "get it" that what is commonly called "leakage" is not actually leakage but light drawn from the pavilion, and that is precisely the problem. I think consumers would respond quite differently to being told that a diamond they are considering draws light from the pavilion than to being told that the diamond has a lot of "leakage" and the post that started this thread is a case in point.

I don't know if you know that I was a PS consumer for many years before becoming a trade member.
I have a pretty good idea about what they get and don't get.

As far as properly defining "leakage" I agree with you that the term is not the best term which is why I am the one that points out that it is not leakage in a window sense the vast majority of the time.

Btw We agree on ASET far more than you know. But throwing the baby out with the bathwater is not good either.
Which is why I asked for your and David's help in seeing how ASET can help with radiants.
The AGS cut grade that was based on rounds then applied to fancies I have little use for.
The round grades are decent, princess grades ok, the rest are well just say not that useful.
However the ASET tool is just a tool.
How to apply that tool to different cuts is about interpretation.
I would like to hear your interpretation of ASET on cuts your an expert in because I think I can learn from them.

 

[RADIANTMAN]

Karl - since I don't at this time use ASETs as an evaluation tool for my diamonds (which consumers generally have the opportunity to see in real life before buying), I don't have examples of ASETs readily available - otherwise I would be happy to share them.

I think you are correct that we (all of us posting here) agree more than we disagree about the limitations of ASET which is why the discussion is focused more on the language used to describe the meaning of the data rather than on the data itself.

In general, I think the "science" of cut is extremely valuable for the purpose of helping to develop new cutting styles (as you have and Garry's cut group is doing) without having to experiment as much on actual diamonds (as my Dad had to at great cost). I do not find it nearly as useful as a cut grading too or as a tool to compare different shapes and cutting styles. As a case in point - I don't think comparing light return/leakage between a radiant and an emerald cut is at all a useful exercise. The two cutting styles are intended to reflect light completely differently and which is "nicer" is entirely a matter of personal preference not of "science."

I completely agree, for example, that most fancy shapes have more "leakage" and less "light return" than well cut round brilliants. Personally, I consider that a pretty irrelevant observation - it does not mean that rounds are "better" or more beautiful and to the extent "science" rather than actual visual appearance is utilized to prove that a particular cutting style is visually superior I think the "science" becomes more marketing tool than objective fact.

 

[Rockdiamond]

I will add to Stan's excellent post:
About buying- Garry has suggested numerous times how I could benefit using ASET to purchase fancy shapes.
I do have one sitting here on the desk- it was quite dusty till ysssss asked about leakage.

I keep stressing the point that evaluating diamonds cut for light performance using aset is far more intuitive than for "regular" well cut Fancy Shapes.
Here's why my aset got dusty after trying to follow Garry suggestion a few years back: basically, I'd pick a stone based on the visuals, then look at the stone in the ASET.
The results are simply inconsistent.
Sometimes a band of red across the center is visible in real life, stereoscopic vision, sometimes not.
I've also found that red bands or larger red areas among a primarily green aset can be a problem.
But not always.

These aspects make calibration extremely difficult.
So in a sense, diamond cut education on PS has been boiled down to:
If we can't make some sort of a system that works for well cut radiant cuts, let's use science and buy the best cut diamond, one with a lot of red. And MAKE SURE TO GET AN ASET.

I totally get that a lot of consumers are buying blind. I also get the fact that by virtue of having and using an ASET, a seller is proving they care about quality in cut and their clients. A very good thing.
But lack of ASET is nothing sinister whatsoever. Unfortunately it's for sure that "bad" sellers are not going to use an ASET. But lack of aset, in itself, does it mean a seller is not committed to well cut, beautiful diamonds.
So figuring out better ways of assessment will benefit everyone- even some of the vendors who've been pretty tough on me in this very thread.

 

[Texas Leaguer]

ASET leakage does not equal to Human Stereo Vision leakage.
If ASET shows leakage it does not proof leakage in Stereo Vision.
It is big ASET weakness .

ASET image is not enough to do decision about Fancy cuts( neither positive nor negative)

Serg,
It does make sense given the discussion about cyclops vs stereo vision. Do you have tools to graphically demonstrate this?

 

[RADIANTMAN]

Hi David. You touched on an important point - the idea that the fact that a vendor provides ASET scans for their diamonds somehow indicates that they are more committed to providing their customers with well cut diamonds than those who do not. Providing ASET scans indicates to me only that the vendor is incorporating the language of cut into their marketing. It does not necessarily mean the vendor is either knowledgeable or honest about cut issues. And many vendors who do not provide ASETs are quite knowledgeable and honest.

I believe that Karl is knowledgeable and honest not because he provides ASETs (assuming he does) but because his posts here on this thread reflect (to me) both those characteristics. I believe that you are knowledgeable and honest because we have known each other for years. In neither case is my opinion affected in any way by anyone's choice to use or not use ASET or any other tool in their marketing. It is only when marketing tools are misused either to promote one's own product or to impugn unfairly the products of others that I can draw negative conclusions.

 

[Texas Leaguer]

Hi David. You touched on an important point - the idea that the fact that a vendor provides ASET scans for their diamonds somehow indicates that they are more committed to providing their customers with well cut diamonds than those who do not. Providing ASET scans indicates to me only that the vendor is incorporating the language of cut into their marketing. It does not necessarily mean the vendor is either knowledgeable or honest about cut issues. And many vendors who do not provide ASETs are quite knowledgeable and honest.

I believe that Karl is knowledgeable and honest not because he provides ASETs (assuming he does) but because his posts here on this thread reflect (to me) both those characteristics. I believe that you are knowledgeable and honest because we have known each other for years. In neither case is my opinion affected in any way by anyone's choice to use or not use ASET or any other tool in their marketing. It is only when marketing tools are misused either to promote one's own product or to impugn unfairly the products of others that I can draw negative conclusions.

Stan,
I cannot disagree with the above, but I think there is great value for a seller incorporating a discussion of cut into the value proposition of the diamonds being offered.

You may wish to attribute it to "marketing" but providing ASET, or magnified photos, or videos is really about communicating various visual and light performance aspects about the diamond. A lab report is a "marketing" tool in the same sense.

The fact that a GIA report gives you minimal information about light performance makes other tests and sources of information necessary, especially for internet shoppers. It's a given that the tests need to be interpreted properly to be of value. Any technicial can take an X-ray, but it needs to be read by a radiologist before it is actionable.

What we need is is better collective understanding of what these tests mean for fancy cut diamonds.

 

[Rockdiamond]

See- that's where terminology is so important.
Bryan- you mention "Marketing"- which earned quotes.......yet light performance is not given quotations.
I totally get Stan's point. Cut quality, like things Bryan mentioned, IS a marketing tool
I don't 100% agree with all that Stan wrote- as I'm using sellers that focus on cut quality, to any extent, as more of a litmus test.
But I believe Stan is stating it better than I.
Focusing on cut quality may be a good indicator- but it's not a guarantee that a seller is honest and knowledgeable.