Light leakage, how can you tell in real life?

[yasssss]

Hi experts! so I know you can tell if a stone has light leakage from an aset image, but how do you tell in real life with a princess? i actually feel like there is a not a lot of light leakage in my stone at all because in most lighting it sparkles from corner to corner, but sometimes in photos it looks dark , but that may be the reflection? i was just wondering if there were photos or something that showed examples of leakage. I love my glittery stone and get compliments on how sparkly it is all the time, all this pricescope reading has me wondering though how this looks like in a real life perspective

 

[Gypsy]

you can buy an.aset scipe.

 

[Lorelei]

Hi experts! so I know you can tell if a stone has light leakage from an aset image, but how do you tell in real life with a princess? i actually feel like there is a not a lot of light leakage in my stone at all because in most lighting it sparkles from corner to corner, but sometimes in photos it looks dark , but that may be the reflection? i was just wondering if there were photos or something that showed examples of leakage. I love my glittery stone and get compliments on how sparkly it is all the time, all this pricescope reading has me wondering though how this looks like in a real life perspective

Hi Yasssss,

In real life as Gypsy mentions, you can buy an ASET scope which will tell you more, otherwise it's hard without being able to see the stone in real life as leakage can present in various ways. All diamonds can look darker in some lighting conditions such as bright sunlight or from the shadow of the camera in photos, this could be the case with your Princess. The only way to know for sure is to get an ASET which will break down the components of the optics for you to analyse, otherwise as you love your diamond, try not to worry about it, it sounds like a glittery beauty!

 

[teobdl]

Good Old Gold has great videos showing leakage. For example, https://www.youtube.com/watch?v=mWeladbtUrw . Around 1:15 you see the IdealScope images for the diamond w/ leakage and the diamond w/o any leakage. The differences are "hairsplitting," in the words of Jonathan. Honestly, I doubt anyone could tell you there is leakage if they didn't see the IdealScope. Some leakage is fine, other times it's not. I don't have enough expertise to know the threshold at which you start seeing effects in real life. Obviously, the better the image, the safer you'll be.

Leakage becomes obvious when the IdealScope is terrible. Examples here https://www.youtube.com/watch?v=5iJvva6kSW8 , https://www.youtube.com/watch?v=igm88vMrPR8

 

[Diamond_Hawk]

Yasssss,

As you have heard from above (and as seen in the videos) leakage is most reliably found by the use of an ASET. While under the lights of a diamond showroom, or in bright sunlight the naked eye might not detect significant difference, stones with significant leakage will suffer (by definition) from less light-return.

So it follows that diamonds with leakage will have a difficult time performing in low-light settings --> [less light + less actual return of the available light = poor performance].

So a diamond with leakage when seen in a low-light environment (at a romantic dinner, on a late-evening walk, or while spelunking) will suffer from less light return particularly at the edges of the diamond (making it appear smaller than it is), at the center of the diamond (making it appear darker that it is) or both.

This is why the cut of the diamond is so very, very important for quality presentation in all environments.

 

[Rockdiamond]

I have a slightly different take on this one.....
The term "leakage" when applied to the way a diamond uses light is clearly not a literal one.
The ASET for a round brilliant will show you where diamond apparently allows light to pass unimpeded ( leak). On round diamonds we know what the patterns should be, and they show as very minor areas on truly well cut round diamonds.
Princess cuts are an entirely different type of cut in many cases. There are a lot of really nice looking princess cuts that may exhibit "leakage" in an ASET, yet look perfectly fine in real life.
The ASET provides consistent information, based on a stable and consistent light source, and controlled color environment..
Real life provides inconsistent viewing angles and light sources. Real life includes many other colors introduced into your diamond.
Not to say that there's not some truly horrid cuts out there- and a lot of them- and furthermore, some of them can be easily identified with ASET
But those are also the ones you can easily identify by eye.
Basically, yasssss- if you love the way your diamond behaves having never looked at an ASET, no need to ever look at one. If you've taken a little time to educate your eye, and you're looking at a diamond in real life, and you love it, the ASET should have no part in changing that.
Moving forward, there's plenty of great info on how to identify really badly cut stones with ASET on here.
But from the way you describe it, yours sounds like a nice stone.
Forget about trying to take good pictures of diamonds, that's a full time job- and princess cuts are a bee-atch in general to capture.

Brian- I have to respectfully disagree with a point you made
snip

So it follows that diamonds with leakage will have a difficult time performing in low-light settings --> [less light + less actual return of the available light = poor performance].

Many of the stones that can be shown to be less bright using ASET actually do better in lower lighting. ASET rewards diamonds for reflecting back the brightest light- which is assumed to be overhead.
That's not the case in a dimly lit restaurant. Which is why some older stones, clearly not as "well cut" as some of the amazing stuff coming out nowadays still looks amazing in candlelight ( among other places) precisely because they are gathering light from lower angles.

 

[yasssss]

wow this was all incredibly informative. thank you everyone. and you're right RockDiamond, photos dont at all do my stone justice! My fiance said he looked at aset images before he purchased the diamond, but now that i've been happily wearing it, I'm not going to ask him to see them lol that might be a little weird to him , so I was just musing over its real life performance. Its fun educating yourself on this stuff and it will definitely help in future purchases, but it makes you a little obsessive! can't help it! it also makes you notice other people's diamonds in an entirely different way, i've noticed cloudiness, color, huge inclusions, dullness, etc. and it makes me appreciate my sparkly beauty so much more !

Now, my ethnic jewelry with diamonds, thats a whole different story! but with that diamonds are just one element, so they don't stand out the way a diamond on an eRing does.

Anyway, thanks everyone for indulging me! i'll make my fiance take me somewhere romantic so that I can observe my ring in dim lighting win, win!

 

[MelisendeDiamonds]

wow this was all incredibly informative. thank you everyone. and you're right RockDiamond, photos dont at all do my stone justice! My fiance said he looked at aset images before he purchased the diamond, but now that i've been happily wearing it, I'm not going to ask him to see them lol that might be a little weird to him , so I was just musing over its real life performance. Its fun educating yourself on this stuff and it will definitely help in future purchases, but it makes you a little obsessive! can't help it! it also makes you notice other people's diamonds in an entirely different way, i've noticed cloudiness, color, huge inclusions, dullness, etc. and it makes me appreciate my sparkly beauty so much more !

Now, my ethnic jewelry with diamonds, thats a whole different story! but with that diamonds are just one element, so they don't stand out the way a diamond on an eRing does.

Anyway, thanks everyone for indulging me! i'll make my fiance take me somewhere romantic so that I can observe my ring in dim lighting win, win!

Here is a simple way. Take a piece of red cloth or paper and put it underneath the culet of your diamond. If you see Red those areas are the ones acting like windows instead of mirrors and are leaking light through the bottom.

 

[Diamond_Hawk]

The ASET provides consistent information, based on a stable and consistent light source, and controlled color environment.. Real life provides inconsistent viewing angles and light sources. Real life includes many other colors introduced into your diamond.

Hi Rockdiamond.

It sounds like you may not know the purpose of the ASET? Sorry if I'm mistaken, but "many other colors" (meaning real-life hues) are irrelevant. We all know a diamond 'sees' different hues due to the shirt someone's wearing, the color of the wall, etc.. But that has no meaning in terms of what the ASET is showing us. The purpose of the angular-coding on ASET is to show where the diamond draws its light, not to represent how real life "colors introduced into your diamond" will appear.

ASET is a structured and repeatable environment. The premise is that our world is lit from above the flat 0-degree in a hemisphere. Frequently with brightest light coming from 45-75 degrees (coded as red). Often-also with light coming from 0-45 degrees (coded as green) and always with some obscuration by head and body of viewer (coded as blue). Leakage is seen as white (when backlit) or black (when non-backlit) and is undesirable because those facets perform as windows...passing light through the stone, causing "dead" spots. Admittedly, this is a ‘moment in time’ static picture - showing "potential" of optical performance - but that face-up position is considered the most important and impactful and is the foundation of all grading metrics and studies.

Many of the stones that can be shown to be less bright using ASET actually do better in lower lighting. ASET rewards diamonds for reflecting back the brightest light- which is assumed to be overhead. That's not the case in a dimly lit restaurant. Which is why some older stones, clearly not as "well cut" as some of the amazing stuff coming out nowadays still looks amazing in candlelight ( among other places) precisely because they are gathering light from lower angles.

We don't disagree at all! In fact this supports the ASET premise.

If someone literally lives in a dimly lit restaurant with side-lighting coming from below 45 degrees they may want to seek a diamond with more green than red in the picture. But if that person will ever exit the restaurant and walk around in real-world daylight, office light, home light, beach, river, forest, cityscape, etc., a fancy-shaped diamond with a strong balance of red (esp) and green in ASET will perform better through all of those conditions.

As I often say, greens are not bad in an ASET. This is why the disparity on fancy cuts in ASET opinions happens: The ‘sometimes’ assumption that a primarily green ASET on a fancy cut is bad…no, I disagree with that. While red is preferred, green is still performance and if it is green to the edges and through the middle, with little leakage, and even/balanced contrast it's going to perform well in the majority of lighting situations.

Red – Great
Green – Good
Blue – Necessary and desired (esp. if balanced and symmetrical)
Leakage – Bad.

The point is that a balanced ASET, with minimized leakage, identifies diamonds expected to perform well through the most possible lighting conditions in our world.

 

[Rockdiamond]

HI Brian,
I am completely familiar with the premise behind the ASET, as well as how it works. We agree it can provide a consistent "benchmark" because it eliminates variables.
This is both a strong and weak point.
I stand by my statement that real life info is very important when considering the cut of a diamond. How a diamond reacts when it's being worn matters.
How it reacts to setting matters.

In fact, I do feel that how diamond looks in real life- as opposed to in a reflector is more important to me when I'm buying.
That's why it's far more informative studying a diamond first hand, as opposed to an ASET image. It's also far more informative to examine a diamond through a loupe, and in various lighting environments as opposed to an aset.
That's the most impactful and meaningful study a person actually buying a diamond can do.

Just to be clear about your statement:

Red – Great
Green – Good
Blue – Necessary and desired (esp. if balanced and symmetrical)
Leakage – Bad.

Based on this logic, a Radiant cut with more red has a better cut than one with more green. Is that what you meant?

 

[Diamond_Hawk]

HI Brian, I am completely familiar with the premise behind the ASET, as well as how it works. We agree it can provide a consistent "benchmark" because it eliminates variables.

I get it - no problem. I only asked because you mixed a comment about its “controlled color environment” with a reference to colors in real life, which have nothing to do with interpreting ASET information.

I stand by my statement that real life info is very important when considering the cut of a diamond. How a diamond reacts when it's being worn matters. How it reacts to setting matters. In fact, I do feel that how diamond looks in real life- as opposed to in a reflector is more important to me when I'm buying. That's why it's far more informative studying a diamond first hand, as opposed to an ASET image. It's also far more informative to examine a diamond through a loupe, and in various lighting environments as opposed to an aset. That's the most impactful and meaningful study a person actually buying a diamond can do.

Right. Again I don’t disagree. Real-life examination is the best environment, but you can learn a great deal by referencing real-life views to what you see in the ASET. And this goes both ways, meaning the more you look at a given shape in the loupe + real-life multi lighting + ASET the more you can interpret-from-afar in an ASET.

Just to be clear about your statement:
“Red – Great
Green – Good
Blue – Necessary and desired (esp. if balanced and symmetrical) Leakage – Bad.”
Based on this logic, a Radiant cut with more red has a better cut than one with more green. Is that what you meant?

That is impossible to say. Context is important. I could ask you “Is a diamond with a crystal inclusion more desirable than one with a feather inclusion?” You’d need more context, just as I would to answer this situation. There are too many variables, especially given the importance of facet structure in the shape and how the angular spectrum is distributed.

 

[Rockdiamond]

I'm sure we agree on most things Brian. I appreciate the thoughtful discourse.
My point ( which my apologies, could have been far better stated) is that the belief that red is just "better" than green in fancy shapes is expressed all too often with no context. For example, red in the middle can sometimes indicate a big problem area ( IMO ) in some square modified brilliant diamonds, be they Radiant, Princess or Cushion.
When it comes to brilliance, the aset again provides that controlled environment- which can be interpreted in a far more logical manner on a round brilliant diamond- or some of the variant ideal cut stones such as an AGS 0 princess
But not on a "crushed ice" stone ( I hate to use that maligned term here) .
Another example of desirable fancy shaped stones with a lot of green might be a pear shape modified brilliant. The type cut with additional light bounces. Yes, it's less brilliant as measured by ASET but still preferable to many because it might be spreadier, and exhibit no bowtie.
In a real sense, when it's boiled down to "red is preferable, but green is ok", it kind of defeats the purpose of ASET technology.

This is way late Brian, but if i did not say it before, welcome to PS

 

[Garry H (Cut Nut)]

Nice discussion.
The top 3/4 of your first post was very good Rockdiamond.
The last half was wrong advice for Yasss because in the leakage zones there can be no light return, Does not matter if it is a candle lit dinner and 5 bottles of wine. The exception is if one eye can see leakage (i.e. slightly tilted ASET) and the other sees red or green (but not blue) (slightly tilted the other way). My recent work on some heavy artilces with my Cut Group associates and some of Sergey and Yuri's boffins has highlighted the idea that if one eye sees brigtness and the other does not then the confusion in the brain creates the hightened illusion of brilliance.
For that reason, before I knew about binocular rivalry, I made these videos to show you how best to select princess cuts with ASET http://www.ideal-scope.com/using_reference_chart_ASET.asp and http://www.ideal-scope.com/1.using_fancy.asp and I think there is one other relevant part there somewhere.

Yasss I hope that helps

 

[Diamond_Hawk]

Thanks for the welcome – it is a great community.

the belief that red is just "better" than green in fancy shapes is expressed all too often with no context.

I agree whole-heartedly – a point I try to make often.

When it comes to brilliance, the aset again provides that controlled environment- which can be interpreted in a far more logical manner on a round brilliant diamond- or some of the variant ideal cut stones such as an AGS 0 princess

We are almost in agreement here – the word ‘logical’ is a sticking point for me, I guess. Perhaps the word “straight-forward” or “elementary” is more in line with how I would phrase it. There is, of course, logic to all of it, but different shapes call for more hands-on experience and sampling. This is – again - no different than interpreting clarity; it is very straight-forward for some diamonds, but takes hands-on experience and sampling for others.

In a real sense, when it's boiled down to "red is preferable, but green is ok", it kind of defeats the purpose of ASET technology

Let’s be very clear here. If you are saying that ‘too many people’ make this assertion, I can agree, but I never said those words. I described Red as Great and Green as Good and the distinction there is important.

Here is what I said:

As I often say, greens are not bad in an ASET. This is why the disparity on fancy cuts in ASET opinions happens: The ‘sometimes’ assumption that a primarily green ASET on a fancy cut is bad…no, I disagree with that.

It comes to this: If someone is viewing a diamond (fancy-shaped or MRB) that shows quality light return throughout the ASET image (Red, Great – Green, Good with positive/balanced Blue contrast effects) it will do well in all lighting environments. If the diamond demonstrates leakage at the edges, under the table, or in too much abundance overall, that diamond will seem smaller and/or darker than the one with quality light return, esp in low-lighting environments.

 

[Diamond_Hawk]

Garry, that is a dynamite reference page. Comment and question.

http://www.ideal-scope.com/1.using_reference_chart_ASET.asp

I think the tilt movies are an eye-popping illustration of leakage zone impact from left to right, especially under the tables.

My question is how much do you think non-backlit ASET photos hide leakage in fancy shapes?

 

[WinkHPD]

Wow!

Brian, it is obvious that you have made a serious study of diamond cutting and it has been a pleasure to read the discussion with you and Rockdiamond.

The one thing that both of you have not mentioned yet is that even a little bit of dirt will greatly increase those areas of leakage. Even for an excellent cut diamond to perform well, it needs to be clean, especially in low light conditions. It takes very little smudging on the top of a diamond to rob it of its sparkle.

Ladies, if you get a fantastic cut diamond and do not clean it often, you are depriving yourself of the beauty of the cutters art!

Wink

 

[Diamond_Hawk]

Wow!

Brian, it is obvious that you have made a serious study of diamond cutting and it has been a pleasure to read the discussion with you and Rockdiamond.

A lot ( and I mean a lot ) of the 'serious study' is related to reading and re-reading previous threads, articles and links posted here on PriceScope over several years. People like you, Wink, make it easy to find answers, and develop opinions and philosophies in order to speak intelligently on these types of things.

The one thing that both of you have not mentioned yet is that even a little bit of dirt will greatly increase those areas of leakage. Even for an excellent cut diamond to perform well, it needs to be clean, especially in low light conditions. It takes very little smudging on the top of a diamond to rob it of its sparkle.

Ladies, if you get a fantastic cut diamond and do not clean it often, you are depriving yourself of the beauty of the cutters art!

+1

 

[Rockdiamond]

WINK!!
HI
Garry- also very nice to "see" you.
Brian....
Gentlemen, I do have one request, while I appreciate the use of our corporate name ( my screen name), please call me David.

Brian- I find an inconsistency in these two statements of yours
This:

While red is preferred, green is still performance and if it is green to the edges and through the middle, with little leakage, and even/balanced contrast it's going to perform well in the majority of lighting situations.

And this exchange:

my statement: the belief that red is just "better" than green in fancy shapes is expressed all too often with no context.

your response
I agree whole-heartedly – a point I try to make often.

It seems pretty plain to me that you are stating that red is preferred, and green is lesser. You gave some context, yet not nearly enough.
The opening of your statement is what many will take away.
It will boil down to: red is better.

Red is not better.

In fact, the whole discussion of which fancy shape is possesses the "best" cut is like a discussion of the merits of chocolate versus vanilla.
We can all agree to leave out the sour melted stuff from my analogy. There's PLENTY of horribly cut fancy shapes- I'm sure we all agree on that.

The whole point is, how does a consumer choose from the range of well cut stones out there?
I think that if a consumer uses aset in the standard PS method- by posting aset pics and asking which is the best - this method will not produce the same results as if the person was looking at actual diamonds.
IOW -A consumer looking at 10 ASET photos, having gotten the idea how to judge ASET here on PS- and the ten actual diamonds. Many might choose different diamonds based on the actual visual.
In my opinion, it's more about incorrect interpretation of ASET as opposed to a criticism of the science of the device.

 

[Rockdiamond]

Garry- thanks for posting the link. It does make for interesting conversation
A screen shot so we can all look at it for discussion.
From my perspective, the terminology makes a huge difference.
The terms "Excellent, Very Good, Good, and Fair.
Are they based on AGSL definitions?

I will say that the stone termed Fair might be a beautiful stone

 

[Texas Leaguer]

WINK!!
HI
Garry- also very nice to "see" you.
Brian....
Gentlemen, I do have one request, while I appreciate the use of our corporate name ( my screen name), please call me David.

Brian- I find an inconsistency in these two statements of yours
This:

While red is preferred, green is still performance and if it is green to the edges and through the middle, with little leakage, and even/balanced contrast it's going to perform well in the majority of lighting situations.

And this exchange:

my statement: the belief that red is just "better" than green in fancy shapes is expressed all too often with no context.

your response
I agree whole-heartedly – a point I try to make often.

It seems pretty plain to me that you are stating that red is preferred, and green is lesser. You gave some context, yet not nearly enough.
The opening of your statement is what many will take away.
It will boil down to: red is better.

Red is not better.

In fact, the whole discussion of which fancy shape is possesses the "best" cut is like a discussion of the merits of chocolate versus vanilla.
We can all agree to leave out the sour melted stuff from my analogy. There's PLENTY of horribly cut fancy shapes- I'm sure we all agree on that.

The whole point is, how does a consumer choose from the range of well cut stones out there?
I think that if a consumer uses aset in the standard PS method- by posting aset pics and asking which is the best - this method will not produce the same results as if the person was looking at actual diamonds.
IOW -A consumer looking at 10 ASET photos, having gotten the idea how to judge ASET here on PS- and the ten actual diamonds. Many might choose different diamonds based on the actual visual.
In my opinion, it's more about incorrect interpretation of ASET as opposed to a criticism of the science of the device.

Hi David,
I think Brian made his points about ASET and he provided context (not enough for you apparently) and he patiently provided support for what he was stating. On the other hand, I find many of your statements to be inconsistent and sometimes difficult to fathom. I really don't know where you are going with some of your arguments when you keep stressing, in this thread and many others, the importance of looking at the actual diamond. Nobody is arguing that point. At all.

Meanwhile, we discuss various aspects of light performance and the tools and methodologies to break down and assess diamond beauty. And we employ those tools which are useful for remote discussion about diamonds. But nobody is arguing that one should ONLY use ASET to evaluate a diamond. And while red represents brightness, nobody is saying that diamonds should be all red- in fact everyone explicitly recognizes that balance is necessary for the most beautiful diamonds. And they acknowledge that different shapes and facet arrangements have different signatures in ASET. Some of the best fancies may have a lot of green, for example. You may have a different preference for what that optimal balance is, and that is fine. We don't all like the same things, but we can discuss them in a detailed way that creates greater understanding for all. The fact that I like chocolate and you like vanilla should not prevent us from analyzing the ingredients that make the two flavors taste differently.

So if you have a different interpretation of an ASET that is being discussed, by all means let it be known along with your reasoning. And if you want to make the case that the leakage is good, and red is bad, have at it. If you have no criticism of the science behind ASET, then one would think you would view it as a useful tool for discussing diamonds that are not in front of you to be able to assess with your trained eye. Instead however, you seem determined to discount the value of the tools that inform us about the different aspects of light performance- the components of diamond beauty.

We have many tools that we use collectively to evaluate diamonds. Some provide more information than others. You put various pieces of information together, including visual inspection, for a comprehensive understanding of a diamond. The fact that the customer's eye is the final arbiter of diamond beauty does not mean that scientific analysis by multiple tools is not of high value to the selection process.

Aside from a small subset of diamond connoisseurs including many prosumers on this site, most consumers, by definition, are not experts and do not have a trained eye for diamonds. So they instinctively seek more sources of information to have confidence in their purchases.

 

[Garry H (Cut Nut)]

Garry, that is a dynamite reference page. Comment and question.

http://www.ideal-scope.com/1.using_reference_chart_ASET.asp

I think the tilt movies are an eye-popping illustration of leakage zone impact from left to right, especially under the tables.

My question is how much do you think non-backlit ASET photos hide leakage in fancy shapes?

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 H (Cut Nut)]

Wow!

The one thing that both of you have not mentioned yet is that even a little bit of dirt will greatly increase those areas of leakage. Even for an excellent cut diamond to perform well, it needs to be clean, especially in low light conditions. It takes very little smudging on the top of a diamond to rob it of its sparkle.

Ladies, if you get a fantastic cut diamond and do not clean it often, you are depriving yourself of the beauty of the cutters art!

Wink

Thanks Wink, further justification for shallower cuts that leak less when dirty. Along with my post above - perhaps I need to shift HCA even shallower hahahaha

 

[Garry H (Cut Nut)]

Garry- thanks for posting the link. It does make for interesting conversation
A screen shot so we can all look at it for discussion.
From my perspective, the terminology makes a huge difference.
The terms "Excellent, Very Good, Good, and Fair.
Are they based on AGSL definitions?

I will say that the stone termed Fair might be a beautiful stone

The fair stone would be the best for a fancy color stone. It could also be good as a shoulder stone for a FCD - since setting really bright stones next to well cut fancies (that have only ASET green and very small leakage zones) is bad.

 

[Rockdiamond]

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?

 

[Garry H (Cut Nut)]

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?

ASET, HCA and Ideal-scope should best be used as rejection tools to narrow down to the best most likely stone to be good.
There are no objective cut grading systems that match human perception for beauty. There may not be for a decade or more.

 

[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?

 

[RandG]

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?

I just want to thank you for your insightful and candid posts within this thread-- they offer a great deal of balance I find sometimes lacking but extremely beneficial for novice consumers. All well said, and very important points for this community. I appreciate it!

 

[yasssss]

I just want to thank you for your insightful and candid posts within this thread-- they offer a great deal of balance I find sometimes lacking but extremely beneficial for novice consumers. All well said, and very important points for this community. I appreciate it!

+1

Thank you!

 

[Rockdiamond]

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?

ASET, HCA and Ideal-scope should best be used as rejection tools to narrow down to the best most likely stone to be good.
There are no objective cut grading systems that match human perception for beauty. There may not be for a decade or more.

Garry- I doubt that we humans will ever be able to agree on an objective, scientific system to grade Beauty. In 10 years or 10,000.
About the ASET being used for rejection. ( no one mentioned HCA and we're talking about fancy shapes anyway, so it's not relevant)
I's a GREAT tool for that- BUT- first the user need to know what they want to reject. To get to that point, the interpretation of the images needs to be done in a far more scientific, objective manner

 

[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.
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