Discussion of green in an ASET image

[Rockdiamond]

Is green bad in an aset?
I've heard that said on a number of occasions.

I'll use examples of stones that meet the guidelines for posting here on PS ( not available on our site)
I'll start with a marquise.
Here's my impression of how to interpret this aset, looking at the actual stone, and the aset image:
The green areas are "crushed ice" looking. That is to say, small virtual facets, flashing back a lot of pinfire. The aset does give a pretty good idea of the bowtie- which this stone does exhibit.
In any even, the tips of the stone- where there's a lot of green on the aset- are the "flashy" part.
Subjective : looking at the stone in person, I like the parts that show green on the aset


Below I've photographed the stone with the pavilion blocked to allow context.

 

[ChunkyCushionLover]

Is green bad in an aset?
Below I've photographed the stone with the pavilion blocked to allow context.

RD,

1) Never compare pavilion lit shots to an ASET image they will not correlate properly. No tweezers shots. The ASET does not color light passing one way through its pavilion.

2) The ASET shows where a facet can be illuminated from the hemisphere above it and reflects colored light of different angles that travel through its crown.

3) Green by itself does not mean smaller flash. The ASET is not a tool for definitively illustrating virtual facet size. A photograph or ray trace simulation is much better for this.



There are hundreds of tiny VFs in the star108 and not much green.
You can have very tiny flashes that represent an area that is Red or Green in the ASET.

4) Green areas as seen in an ASET can be lit up if low angle light is available, (Side lamp, light bouncing off walls etc.).
In your pavilion blocked shot most of the green areas are not being lit up, I see what is underneath the stone in most of the areas at the bottom.

Areas that are green will be observed the same as white areas in the absence of low angle light.
---------------------------

I have put time and effort into this post, I don't believe this is research or breaking new ground. I wrote it so that I could guide you into proper interpretation of ASET images, this discussion focuses exclusively on brightness and potential brightness only, no other diamond properties.

I hope you will paraphrase all four points properly and indicate your understanding in a reply before we move on so that I know you are reading and interpreting properly what I am trying to teach you. This can be the start for common ground and understanding.

 

[Regular Guy]

I hope you will paraphrase all four points properly and indicate your understanding in a reply before we move on so that I know you are reading and interpreting properly what I am trying to teach you. This can be the start for common ground and understanding.

Sorry, CCL, I understand in this new forum, the focus will best be content...but....despite what may well be your superior understanding, the size of the chip on your shoulder makes the content difficult to make out. That participation in a thread begun by another is optional is a further confound.

Just my 2 cents.

Ira Z.

 

[Garry H (Cut Nut)]

Is green bad in an aset?
I've heard that said on a number of occasions.

I'll use examples of stones that meet the guidelines for posting here on PS ( not available on our site)
I'll start with a marquise.
Here's my impression of how to interpret this aset, looking at the actual stone, and the aset image:
The green areas are "crushed ice" looking. That is to say, small virtual facets, flashing back a lot of pinfire. The aset does give a pretty good idea of the bowtie- which this stone does exhibit.
In any even, the tips of the stone- where there's a lot of green on the aset- are the "flashy" part.
Subjective : looking at the stone in person, I like the parts that show green on the aset


Below I've photographed the stone with the pavilion blocked to allow context.

Hi David,
In the recent crushed ice thread I tried to show that all blue and too much red is bad for crushed ice.
Green and well dispersed tiny leakage zones are good because they indicate increased ray path lengths = more tiny virtual facets.
I spent quite a bit of frustrating time to show you that ASET can help you very quickly know if a stone will be a reject for crushed ice or even-ness of fancy color and optimization.
In light of your topic here you might like to re-read some of my posts. You thought and interpreted my posts wrongly.

 

[Garry H (Cut Nut)]

Here is an alteranative that I just bought for a client - a very bright (relative for a marquise) stone with not too much bow tie and a nice +24% spread with no thin girdle.
Most marquise have too much of one effect or the other, and the best stones are at either end - uniformly bright or uniformly crushed ice.

 

[ChunkyCushionLover]

I hope you will paraphrase all four points properly and indicate your understanding in a reply before we move on so that I know you are reading and interpreting properly what I am trying to teach you. This can be the start for common ground and understanding.

Sorry, CCL, I understand in this new forum, the focus will best be content...but....despite what may well be your superior understanding, the size of the chip on your shoulder makes the content difficult to make out. That participation in a thread begun by another is optional is a further confound.

Just my 2 cents.

Ira Z.

You know IRA, I spent my time writing that post with nothing but being helping and education on my mind.
No chip, these things are not my subjective opinion there are 4 paraphrased points from the AGSL research paper and tutorials and some extra commentary from my discussions with those researchers.

If you interpret it as a chip and decide to focus on my bias by attacking this post on a personal level than you are not only not helping David but you are also insulting me and my reason for being on pricescope.

 

[Regular Guy]

CCL, suffice it to say for now, here, that Garry's comments helped to put yours into context.

To help this "diamond research" space remain dedicated to that subject, I'll suggest that for any further comments between us "not on point," we "take it outside." In the next few minutes, I'll plan to start a thread in hangout for that purpose.

Ok, folks continue please and thank you...

Ira Z.

 

[ChunkyCushionLover]

Here is an alteranative that I just bought for a client - a very bright (relative for a marquise) stone with not too much bow tie and a nice +24% spread with no thin girdle.
Most marquise have too much of one effect or the other, and the best stones are at either end - uniformly bright or uniformly crushed ice.

Garry,

What does do you mean by too much of one one effect or the other? What would be the negative effect of a marquise with too many bright areas(other than in spread?)?

It seems intuitive to me, flash size has a lot more to do with white areas than it does green. The white areas seperate the small green areas at the tips(the ones capable of appearing illuminated to the viewer), leading to the "crushed ice" look.

White areas can also seperate red areas into smaller flash areas leading to the same effect do you agree?

 

[Karl_K]

ccl
my time is extremely limited today but I wanted to point you in the right direction.
in DC take a look at the marquise facet outline.
What about it will cause green and leakage in even the best cut ones?
Try a pavilion depth of around 43.9 for a well cut one and 50% for a not so well cut one ASET white.
Then play with the modified ASET turn each color black in turn then check where the red is drawing from by slightly moving the start angles of each color.
You will see something about marquise cut diamonds.
Once you figure it out post the images here for others.

 

[Rockdiamond]

Thanks for all the effort Garry.
Without a doubt, my attitude has been one of resistance- and I apologize- I am very grateful for your participation in any discussion.
We may not agree on some subjective aspects- which I believe makes these exercises far more informative, and interesting.
I am honestly interested in learning more about aset, and how it may fit with my sensibilities. Your technical knowledge is a great addition.
By any chance, do you have any actual photos of the marquise you posted the aset of?

 

[Rockdiamond]

I hope you will paraphrase all four points properly and indicate your understanding in a reply before we move on so that I know you are reading and interpreting properly what I am trying to teach you. This can be the start for common ground and understanding.

Sorry, CCL, I understand in this new forum, the focus will best be content...but....despite what may well be your superior understanding, the size of the chip on your shoulder makes the content difficult to make out. That participation in a thread begun by another is optional is a further confound.

Just my 2 cents.

Ira Z.

Ira, thank you very much.
I resisted from responding in hopes cooler heads would prevail.
ccl- you clearly have a desire to learn, and to share that knowledge.
I have expanded my horizons by taking note of specific in facet design- and some of what you've written helped that.
On the other hand, please do not discount the value of real practical experience. For example, although I now refer to "8main Cushions", for me the distinction is one of words- I have been able to recognize the differences for many years, but now I have more ways to describe them.

Also, please keep in mind that subjective judgement will never be removed from any discussion of beauty in diamonds - or even quality of cut.

In terms of diacalc, and other simulations- I request that we limit this discussion to aset and it's relation to actual diamonds- I will be happy to procure stones specifically for this purpose.
The reason behind this request is to prevent the discussion from getting overly technical- this way more people may get benefit from it.

 

[Regular Guy]

In terms of diacalc, and other simulations- I request that we limit this discussion to aset and it's relation to actual diamonds- I will be happy to procure stones specifically for this purpose.
The reason behind this request is to prevent the discussion from getting overly technical- this way more people may get benefit from it.

To my own way of thinking, despite the fact that you did initiate this thread, RD...it is not yours...you do not possess it. It is now a part of the board. Others, and Paul comes to mind, have asked for the courtesy of directing the thread, and that argument could be made. But, I do not make it. Especially so, on this board now dedicated to diamond research.

No harm, and a potential benefit, for expressing your interest in directing the thread, based on any logic you choose. I'm just saying, as they say in one particular tradition I'm fond of: "you get a vote, but not a veto."

My 2 cents...

Ira Z.

 

[Rockdiamond]

Point well taken Ira.
my line of thinking is based on experience- and CCl's initial post which delves into ray tracing etc.
If we want to explore the reading of aset- and such info helps, than I stand corrected.
However taking one concept at a time may allow a foundation for other concepts to be discussed with better clarity

 

[ChunkyCushionLover]

CCL, suffice it to say for now, here, that Garry's comments helped to put yours into context.

To help this "diamond research" space remain dedicated to that subject, I'll suggest that for any further comments between us "not on point," we "take it outside." In the next few minutes, I'll plan to start a thread in hangout for that purpose.

Ok, folks continue please and thank you...

Ira Z.

I beleive this thread should be about a comprehensive discussion of ASET image interpretation in the green low angle region.
If one wants to ignore interpretation of ASET, the science behind it and move on directly to comparing ASET to subjective beauty evaluations here it is:

Objective Facts:

Small green patches sorrounded by white in ASET can show fast scintillation (abundant small pinfire flashes) in strong spot lighting or lighting with abundant lower angle sources. In other more diffuse overhead only lighting those areas can be lifeless.

Scintillation(sparkles) and brightness are two different things, a stone can have many tiny little pinfire flashes under strong spot lighting and movement but still not appear very bright.

It would be better to correlate ASET white with smaller flashes as those are the areas that create contrast.
NO direct correlation between green with smaller virtual facets or flashes.


Subjective Opinion: I don't beleive brightness has to be sacrificed for faster scintillation.

At the very least a good balance of brightness and scintillation can be achieved by proper facet alignment and design where weight saving and spread considerations do not not overpower more optimal brightness considerations.

By far the status quo in most diamonds with the marquise or pear shape outline is to save weight or to maximize spread and so they are often cut with shallow pavilions.

If we consider a continum of one simplified tradeoff:

<10(Optimal Brightness) --- 9 ---- 8 ---7---6----5---4---3----2---(Optimal Spread)1>

I would say most diamonds on the market today are a 4 or 5 and the ASET would help you choose the 7,8,9,10 from the much more abundant lower numbers. Nothing wrong with going more for spread but you are trading off more intense light return to get it.

Note:

I define brightness using AGSL's definition:

For understanding the illumination appearance of a gem it is useful to think of a gem’s facets and their optical projections,
the virtual facets, as a collection of tiny prisms that direct light to an observer’s eyes. Thus brilliance(brightness) is defined as the percentage by area of such tiny prisms that can direct light to the observer’s eyes.

GIA's definition of brightness is pretty close too:

The appearance or extent of internal and external reflections of "White" light seen in a polished diamond when viewed face-up.

 

[Garry H (Cut Nut)]

In terms of diacalc, and other simulations- I request that we limit this discussion to aset and it's relation to actual diamonds- I will be happy to procure stones specifically for this purpose.
The reason behind this request is to prevent the discussion from getting overly technical- this way more people may get benefit from it.

Sorry David, we are in the research forum now
You will have to either understand DiamCalc - or put up with it.But since the topic is Marquise - why not spend 2 minutes and download the free Demo DiamCalc which only shows a marquise, a fancy yellow cuhion and a round with an inclusion.
Then you could do Karl's experiment under the ASET lighting too.

http://www.octonus.com/oct/download/diam_demo_down.phtml

The marquise is in the male (joke). Will photo when it arrives.

 

[Garry H (Cut Nut)]

CCL in order to get crushed ice you must have longer ray paths. That is what creates the additional virtual facets.

If you must have longer raypaths you must also get a greater amount of leakage.
Anyone who wants a yellow spectrum to play with - sing out - then you can see that even the leakage zones can show great color - but only when the ray paths are longer = more virtual facets = more leakage potential.

Remeber there are many long ray paths that involve partial leakages from each 'bounce'.

 

[Rockdiamond]

Thanks Garry.
I did the download Garry- but for some reason, the program won't open.
Maybe I'll need to re-boot my system then try opening the software.

I promise to keep an open mind.
I'm pressed for time this evening so it might take till tomorrow.

 

[Garry H (Cut Nut)]

Thanks Garry.
I did the download Garry- but for some reason, the program won't open.
Maybe I'll need to re-boot my system then try opening the software.

I promise to keep an open mind.
I'm pressed for time this evening so it might take till tomorrow.

You may have to find the program and launch the thingy ma bob that sets up the program.
It will then show up in "All Programs" as DiamCalc Demo"

 

[ChunkyCushionLover]

CCL in order to get crushed ice you must have longer ray paths. That is what creates the additional virtual facets.

Depends on your definition of crushed ice. I equate all crushed ice with smaller virtual facets, it includes much more than just small VFs caused by longer ray paths. You have constrained crushed ice to only the kind that shows widespread leakage as well, the watery crushed ice Rhino talks about, but not the bright crushed ice type he also mentions.

Smaller virtual facets "bright crushed ice" can also be created by adding more physical facets especially where symmetry is a lower order. The light path need not be longer in this case. Example Star108, Cushette, some types of Radiant and cushion with more than the normal pavilion facets but adequate depth etc.

 

[Karl_K]

Smaller virtual facets "bright crushed ice" can also be created by adding more physical facets especially where symmetry is a lower order. The light path need not be longer in this case. Example Star108, Cushette, some types of Radiant and cushion with more than the normal pavilion facets but adequate depth etc.

I would not classify some of those those as crushed ice the look is totally different.
Star129 looks nothing like crushed ice while having very small VFs in smaller sizes.

 

[Garry H (Cut Nut)]

CCL in order to get crushed ice you must have longer ray paths. That is what creates the additional virtual facets.

Depends on your definition of crushed ice. I equate all crushed ice with smaller virtual facets, it includes much more than just small VFs caused by longer ray paths. You have constrained crushed ice to only the kind that shows widespread leakage as well, the watery crushed ice Rhino talks about, but not the bright crushed ice type he also mentions.

Smaller virtual facets "bright crushed ice" can also be created by adding more physical facets especially where symmetry is a lower order. The light path need not be longer in this case. Example Star108, Cushette, some types of Radiant and cushion with more than the normal pavilion facets but adequate depth etc.

Karl is correct CCL.

I hope this helps - a model of a yellow diamond, and you can see here that I have shot a ray thru the ciercled area which is one of the stronger yello zones because the ray path (set to 40 bounces) is huge - probably averaging 15 times diameter.

I counted all the exit rays and 70% or the light is leaving via the pavilion - 30% above (not counting the 17% reflection).

 

[ChunkyCushionLover]

ccl
my time is extremely limited today but I wanted to point you in the right direction.
in DC take a look at the marquise facet outline.
What about it will cause green and leakage in even the best cut ones?
Try a pavilion depth of around 43.9 for a well cut one and 50% for a not so well cut one ASET white.
Then play with the modified ASET turn each color black in turn then check where the red is drawing from by slightly moving the start angles of each color.
You will see something about marquise cut diamonds.
Once you figure it out post the images here for others.

Sorry Karl I missed this post and your point.
I don't have a poorly cut marquise only the default one in Diamcalc and one other well cut one.

Pavilion depth % only measures the centre mains the other mains are shallower and even more shallow with higher LW ratio.
Answer will be different depending upon LW ratio, crown configuration and other facets.

If using the default marquise in DC and increasing the pavilion depth of the centre mains from default(43%) to about 50% you start to get a bowtie. You also get a similar bowtie if you go more shallow than 43%. Bowtie doesn't seem to be a problem in well cut marquise bowtie areas can be areas of contrast and fire as blue changes to red with slight tilt as is the case for default marquise in DC.

For well cut marquise (LW=1.5) with 14% crown and changing pavilion depth to 50% pavilion centre main bowtie returns light from 88 degrees - 90.

What does this have to do with ASET green?

 

[Karl_K]

ccl
my time is extremely limited today but I wanted to point you in the right direction.
in DC take a look at the marquise facet outline.
What about it will cause green and leakage in even the best cut ones?
Try a pavilion depth of around 43.9 for a well cut one and 50% for a not so well cut one ASET white.
Then play with the modified ASET turn each color black in turn then check where the red is drawing from by slightly moving the start angles of each color.
You will see something about marquise cut diamonds.
Once you figure it out post the images here for others.

Sorry Karl I missed this post and your point.
I don't have a poorly cut marquise only the default one in Diamcalc and one other well cut one.

Pavilion depth % only measures the centre mains the other mains are shallower and even more shallow with higher LW ratio.
Answer will be different depending upon LW ratio, crown configuration and other facets.

If using the default marquise in DC and increasing the pavilion depth of the centre mains from default(43%) to about 50% you start to get a bowtie. You also get a similar bowtie if you go more shallow than 43%. Bowtie doesn't seem to be a problem in well cut marquise bowtie areas can be areas of contrast and fire as blue changes to red with slight tilt as is the case for default marquise in DC.

For well cut marquise (LW=1.5) with 14% crown and changing pavilion depth to 50% pavilion centre main bowtie returns light from 88 degrees - 90.

What does this have to do with ASET green?

leave everything the same and just change the pavilion depth % of the DC standard one.
It has everything to do with green in ASET in a marquise.
Pay attention to the pavilion and where the pavilion reflectors are aimed.
Even if it is red it is right at the red/green border due to long shallow mains going out to the corners being aimed at the green zone, its worse with 50% pavilion depth which is the zone where many are cut.

 

[Karl_K]

43.9%


50%


It is impossible to aim a majority of the virtual facets into the red/blue ASET zone like you can with a RB.
Aim the steep sections into the red zone and the others move out and vis-versa.
Therefor the best cut marquise is going to have green.
The long shallow facets crown and pavilion is also the reason for the leakage.

 

[Karl_K]

In contrast an RB is symmetrical so it is easy to aim all the reflectors into the red zone.

 

[Karl_K]

So in conclusion green in a marquise ASET is a fact of science not a matter of good bad or indifferent.
So now the question becomes much harder.
How much green is too much?

 

[ChunkyCushionLover]

So in conclusion green in a marquise ASET is a fact of science not a matter of good bad or indifferent.
So now the question becomes much harder.
How much green is too much?

You just posted an RB 3 times and didn't post the marquise you must be tired.
43.9% pav depth is superior in both brightness and spread.

Marquise design with 8 mains both on crown and pavilion, with an extra row of girdle breaks to compensate for longer length than width could compensate for this.

 

[Karl_K]

So in conclusion green in a marquise ASET is a fact of science not a matter of good bad or indifferent.
So now the question becomes much harder.
How much green is too much?

You just posted an RB 3 times and didn't post the marquise you must be tired.
43.9% pav depth is superior in both brightness and spread.

Marquise design with 8 mains both on crown and pavilion, with an extra row of girdle breaks to compensate for longer length than width could compensate for this.

first 2 are side view marquise to me?

43.9 takes a large hit in yield which is why most are cut in the 50% area.

There are some other facet designs for a marquise that can pick up more red but there will still be a lot of green.
They were developed to help eliminate the bow tie while allowing the yield of a 50%+ pavilion.

 

[ChunkyCushionLover]

So in conclusion green in a marquise ASET is a fact of science not a matter of good bad or indifferent.
So now the question becomes much harder.
How much green is too much?

You just posted an RB 3 times and didn't post the marquise you must be tired.
43.9% pav depth is superior in both brightness and spread.

Marquise design with 8 mains both on crown and pavilion, with an extra row of girdle breaks to compensate for longer length than width could compensate for this.

first 2 are side view marquise to me?

Sorry I was tired, yes from that view mains look evenly sized and it looked like the image was stretched, now that I looked at the profile in DC it matches the marquise my eyes were playing tricks on me last night. The pavilion view shows how assymetric that design is the mains are, only has twofold symmetry unlike round which has 8fold.

43.9 takes a large hit in yield which is why most are cut in the 50% area.

Can you explain how you know it takes a hit in yield? Intuitively If inside stone(spotted outline) were cut with steeper pavilion angles more rough would be retained. (Assume black outline is rough not already faceted). Top example.

But the opposite would also be true if the rough were more shallow (bottom example) wouldn't it?

 

[Karl_K]

43.9 takes a large hit in yield which is why most are cut in the 50% area.

Can you explain how you know it takes a hit in yield? Intuitively If inside stone(spotted outline) were cut with steeper pavilion angles more rough would be retained. (Assume black outline is rough not already faceted). Top example.

But the opposite would also be true if the rough were more shallow (bottom example) wouldn't it?

The diamond will be cut as dictated by the rough.
If the rough is shallow then the stone will be cut shallower.
If the rough will allow it and it does much of the time a deeper pavilion would be cut to keep the weight.