H&A - pattern vs crispness?

[Lula]

I've been following the thread on stars and lgfs https://www.pricescope.com/communit...ct-diamonds-with-large-lgfs-and-stars.146538/ and something Paul Slegers said in that thread was confusing to me:

"Another side-aspect is that they pay more attention to the actual pattern and less to the crispness of the pattern. In my view, the latter is a clear error, since it is the crispness of the pattern that will have the most positive effect on the observed scintillation and fire."

Rather than clutter up Daniel S's thread, I'm starting a new thread to get more information on this aspect of H&A. To be honest, I thought that if you have a good pattern, you automatically get crispness...but apparently that's not the case?

What are the differences between the two and why would crispness affect scintillation and fire more than pattern? Any photos of an H&A with perfect patterning and lousy crispness (or vice versa)?

 

[Andelain]

I'm tagging this thread so I can find it later easier. I'm interested in the answers myself.


Portree I knew it was you. That avatar gives you away anywhere.

 

[yssie]

I don't understand either - what does "crispness" mean, exactly, in this context?


Thanks Portree you do start interesting threads

 

[Paul-Antwerp]

Thank you, Sara, Andelain and Yssie for your interest in my small comment. This is not easy to explain, and involves an understanding of history, cutting-techniques and optics. This makes the explanation long and complicated, but I will try to be as clear as possible.

First, the history of H&A. The demand for H&A stems from the Japanese market, probably as a side-effect from the local Eightstar-company producing their product. Logically, the first cutters faced with this demand were the Antwerp-cutters, and they had to squeeze the most out of their talent to produce what the Japanese asked for. Because demand was new, hot and growing and the actual lab-grading was not close to the cutters, the first H&A-cutters took no risk in their approach and produced extremely symmetrical diamonds. Because of their super-symmetry, the patterns in these stones were also very crisp.

When the production increased, two Japanese labs set up a branch in Antwerp, which offered the cutters a faster lab-feedback (as opposed to customer-feedback) on their production. This allowed them to search the bottom-borderline where a stone would still get the H&A-grade while the cutter had more room to play. And thus, this was the start of the ever-returning evolution of safely working towards a high quality towards going for the bottom-borderline of a grade, which still brings the premium.

With H&A becoming popular in the US, in the absence of a lab grading H&A in the US, this evolved even further downwards, up to the point of the pictures still being defendable. Some cutters take this even one level further down by simply engraving 'H&A' on the girdle, because they say so, without offering any proof. It is because of this logical evolution that Todd Gray of NiceIce already at the beginning of this decade talked about A- and B-levels of H&A, claiming that there were hardly any A-level H&A's to find anymore.

This evolution downwards is most visible when examining the crispness of various H&A-patterns. Because of the specificity of our own production, I unfortunately cannot illustrate this with picture-examples, since I would be violating forum-rules. Sorry about that.

With knowledge about light-performance of diamonds evolving, it is slowly becoming clear what is the factual benefit of a H&A. The contrast-pattern of the arrows as such is the basis of scintillation. This was clear already for some time, but it was unclear how this worked exactly. The pattern needs to be symmetrical and nicely divided over the stone, and an arrows-pattern in a round happens to respond to this definition. In a round, I think that it is difficult to produce another contrast-pattern (not at all resembling arrows), but in another shape, other contrast-patterns are definitely possible.

The hearts-pattern makes it easier to judge the symmetry, but this still is not the full story.

Looking at various arrows-patterns, one can easily distinguish stones with a very crisp pattern, while in others the borderlines between white and red are relatively fuzzy. This is completely neglected in the traditional assessment of H&A, but it is important for the scintillation of the diamond. The fuzzy borders are caused by minutely small extra virtual facets on this location, a result of slightly less than optimal optical symmetry. These tiny extra virtual facets reduce the snappy on-off-effect of virtual facets when moving the stone, and it results in a clear difference in observed scintillation. At the same time, the tiny virtual facets do not contribute to the observation of fire.

As such, I believe that the crispness of the contrast-pattern is the most important aspect, and less important than the historical rules about the shaping of the pattern. This does not mean however that the historical rules have to be discarded, since a slightly different pattern may have other effects on scintillation.

I hope that this was somewhat clear.

Live long,

 

[yssie]

Thanks Paul, that is informative

The history of the creation of the H&A concept is interesting, as is your explanation of what 'crispness' is and why it matters

Seems like this is best evaluated by a professional in person, as when looking at a picture on the internet it would be harder to distinguish between crispness of pattern and an even slightly out-of-focus camera or an overly optimized image..?

 

[Lula]

Thank you, Paul, for your explanation. I've read it a few times and this is a tough concept to grasp. I have the same question about judging crispness through photographs that yssie does. For example, is it possible, given how much photograph styles (and equipment) vary from vendor to vendor, to judge how accurate a representation the vendor's photo is of the stone's crispness? Or must this be done in person, using a hearts and arrows scope?

And, another question, is it possible for a stone to have perfect hearts (using the definition that Brian Gavin outlined in a PS article https://www.pricescope.com/journal/hearts_and_arrows_diamonds_and_basics_diamond_cutting ) yet lack crispness? In other words, in some cases, could a cutter's emphasis on perfect hearts patterning come with a cost to a stone's crispness? Or am I misunderstanding your post?

And a third question, is crispness related to contrast -- which I define as the sharp on-off, dark-light reflection of the facets as they catch the light and return it as the stone is moved, tipped, etc. -- which may be a crummy definition, but is definitely something I see in my AGS 000 stones(s).

Thanks...

 

[Paul-Antwerp]

Thank you, Paul, for your explanation. I've read it a few times and this is a tough concept to grasp. I have the same question about judging crispness through photographs that yssie does. For example, is it possible, given how much photograph styles (and equipment) vary from vendor to vendor, to judge how accurate a representation the vendor's photo is of the stone's crispness? Or must this be done in person, using a hearts and arrows scope?

And, another question, is it possible for a stone to have perfect hearts (using the definition that Brian Gavin outlined in a PS article https://www.pricescope.com/journal/hearts_and_arrows_diamonds_and_basics_diamond_cutting ) yet lack crispness? In other words, in some cases, could a cutter's emphasis on perfect hearts patterning come with a cost to a stone's crispness? Or am I misunderstanding your post?

And a third question, is crispness related to contrast -- which I define as the sharp on-off, dark-light reflection of the facets as they catch the light and return it as the stone is moved, tipped, etc. -- which may be a crummy definition, but is definitely something I see in my AGS 000 stones(s).

Thanks...

Hi Sara and Yssie, thank you for your questions.

Q.1: regarding the judgment of crispness through photographs. It is obviously easier to make this judgment in real life than through photographs. Various photo-setups make comparisons difficult and some vendors are not spending sufficient time in focusing and centering while photographing their stones. Then again, I would not dismiss the judgment of photographs. Crispness or the lack of is easy to see, once you start paying attention to it.

Q.2: Crispness and the traditional judgment of hearts are not related. One can have either, and in my opinion, crispness is far more important.

Q.3: The reason why I find crispness very important is exactly because it is directly related to contrast. The crisper the optical border, the sharper the on-off-effect. That makes a dramatic difference in observed scintillation.

Live long,

 

[Lula]

Thank you, Paul, for your explanation. I've read it a few times and this is a tough concept to grasp. I have the same question about judging crispness through photographs that yssie does. For example, is it possible, given how much photograph styles (and equipment) vary from vendor to vendor, to judge how accurate a representation the vendor's photo is of the stone's crispness? Or must this be done in person, using a hearts and arrows scope?

And, another question, is it possible for a stone to have perfect hearts (using the definition that Brian Gavin outlined in a PS article https://www.pricescope.com/journal/hearts_and_arrows_diamonds_and_basics_diamond_cutting ) yet lack crispness? In other words, in some cases, could a cutter's emphasis on perfect hearts patterning come with a cost to a stone's crispness? Or am I misunderstanding your post?

And a third question, is crispness related to contrast -- which I define as the sharp on-off, dark-light reflection of the facets as they catch the light and return it as the stone is moved, tipped, etc. -- which may be a crummy definition, but is definitely something I see in my AGS 000 stones(s).

Thanks...

.
Hi Sara and Yssie, thank you for your questions. Thanks, Paul - your answers have clarified what you mean by "crispness"; however, I'm still curious about a few more things -- see my questions to your answers below.

Q.1: regarding the judgment of crispness through photographs. It is obviously easier to make this judgment in real life than through photographs. Various photo-setups make comparisons difficult and some vendors are not spending sufficient time in focusing and centering while photographing their stones. Then again, I would not dismiss the judgment of photographs. Crispness or the lack of is easy to see, once you start paying attention to it. So, if I'm reading this response correctly, one can train one's eye to look for a stone's level of crispness, regardless of the photo setup/quality -- within limits, of course? Can you give us some idea of what you pay attention to when assessing crispness? I know this is tough without relying on photos (forum rules) but if there is a way to describe what you're seeing in words, please share.

Q.2: Crispness and the traditional judgment of hearts are not related. One can have either, and in my opinion, crispness is far more important. Wow. I'm having a hard time wrapping my head around this. We spend a lot of time staring at hearts images here and making assumptions about a diamond's quality based on the quality of the hearts image. Should we be examining the arrows image more closely? I'm trying to determine where clues to crispness my be "housed."

Q.3: The reason why I find crispness very important is exactly because it is directly related to contrast. The crisper the optical border, the sharper the on-off-effect. That makes a dramatic difference in observed scintillation. This makes complete sense to me, having seen this in my own stone, and having "discussed" this on the forum with yssie and Deamer who have seen this in their stones as well. I believe, to my layperson's eyes, that this is truly where the rubber meets the road when we talk about why super-ideals look different from other diamonds. Excuse my ignorance about the term "optical border" -- what is that and where do I find it in a diamond!

Finally, you mentioned at some point that H&A is just one pattern and that crispness may be seen in other "patterns" -- by that I assume you mean other facet patterns, such as OEC patterning or princess patterning (to name just two examples). If this is true, consumers could educate themselves to look for stones other than RBs that display excellent crispness, right?

Gah-- I haven't bent my brain this much on RT in a while! yssie, help me put this into more physics/science terms!

Edited for spelling and grammer -- where's my second cup of coffee?

Live long,

 

[Karl_K]

Hi Paul,
My opinion is that chasing crisp arrow images is kinda like a dog chasing its tail.
fun for the dog but he isn't getting anywhere.
h&a viewers even in person are not precision optical devices like say a microscope or even the IS pro version. They are also very prone to set up errors.

What in my opinion is important is crispness in scintillation.
It is hard to describe but once you see it one tends to go aha!
A crisp one off pattern scintillation adds to a diamonds beauty while muddy scintillation detracts.
Video is the only way to see it remotely but in person is really where it makes a difference.
Large dark or light zones that do not flash within a reasonable amount of tilt but just seem to slide along the surface are deadly to real world diamond performance and what I call muddy scintillation.
This is different from the slower flashes of large virtual facets which flash sharply but slowly as the diamond is tilted.

 

[Karl_K]

woops my lack of Pepsi is shining through.
I am on the same page with Paul when he said:
"Q.3: The reason why I find crispness very important is exactly because it is directly related to contrast. The crisper the optical border, the sharper the on-off-effect. That makes a dramatic difference in observed scintillation."
I just don't agree that the arrow view is going to be meaningful.

 

[Lula]

woops my lack of Pepsi is shining through.
I am on the same page with Paul when he said:
"Q.3: The reason why I find crispness very important is exactly because it is directly related to contrast. The crisper the optical border, the sharper the on-off-effect. That makes a dramatic difference in observed scintillation."
I just don't agree that the arrow view is going to be meaningful.

Thanks, Karl. I think I was the one that brought up the arrow view, not Paul (looking for shortcuts to judge crispness).
Point 3 is the most clear to me in this discussion; however, what the heck does "optical border" mean?

I have seen this "crispness" in my own stones; I also describe it as a "busy-ness" --- the stone is very "alive" and 3-D. When comparing my stone to others' stones, their diamonds appear to be "flat," lacking depth, and looking distinctly more 2-D. Your description of "muddiness" is helpful. "Contrast" may be the technical term, but I am not sure if that is accepted in the trade as a universal term and/or if consumers have any idea what good contrast looks like in a stone.

Note: I do not want to give the impression that this crispness cannot be seen in other facet patterns or that it is only seen in super-ideal RBs. Because it does possible to imagine more or less crisp stones in other shapes -- and that the crisp stone would be more appealing, whether it's an OEC, emerald cut, etc.

 

[Lynn B]

Interesting thread!

I am not sure if this is even relevant... but my first diamond (years ago) was a gorgeous AGS-0 1.53 G/VS2. Killer diamond, truly beautiful. When I upgraded to my current (AGS-0) 2.36 J/SI2, one of the first things I noticed (besides the lovely SIZE difference!) was a difference in what I could only describe as the "crispness" of its hearts and arrows, but especially the arrows, since that's what you usually see. WHY the new stone looked *crisper* to me I never really understood, but I really liked the look. Now, the old diamond was certainly not HAZY or FUZZY in any way... in fact, I was thoroughly delighted with the H and A's when I had it. It was only when I scrutinized the stones side-by-side that I noticed the difference.

 

[yssie]

Hah! Sara I don’t think I’m of much use to anyone right now, I spent the morning vowing vengeance on the (still new to me ‘cause I’ve done everything possible to avoid it) ms office..

But I have many of the same questions you do, I think -

1. Ditto the request to Paul or Karl to describe what to look for? How does a ‘crisp optical border’ manifest – can you describe this in PS-acceptable words so we can try taking a gander? I look at my oecs and the facet meets are well worn, but that is a physical presentation.

2. Would you always see this fuzzy border (or the results of having a fuzzy border), even when the stone is still, or is it something more enigmatic that only becomes apparent when you tilt the stone?
If I understand correctly a fuzzy optical border is a region of tiny virtual facets in close quarters – weak primary refractions. But I’ve always been under the impression that the human eyes can’t see those emissions, especially when bombarded immediately afterward by a big bold flash from an adjacent large virtual facet, so does ‘fuzzy optical border’ translate into something - dunno quite how to describe it, like the pic - when viewing IRL, with a thin greyish not-bright not-dark static zone in between two facets turning on and off as you tilt the stone?

3. Karl – you describe light and dark zones that don’t flash within a reasonable tilt, is this something that can be visualized with an ASET setup? As in, position the ASET at 40d to the plane of the facet in question, tilt through 50d, and if you don’t see a clear shift from green to red you have muddy scintillation?
(Though I realize such precision wouldn’t be possible IRL with the physical ASET setup)

 

[Karl_K]

3. Karl – you describe light and dark zones that don’t flash within a reasonable tilt, is this something that can be visualized with an ASET setup? As in, position the ASET at 40d to the plane of the facet in question, tilt through 50d, and if you don’t see a clear shift from green to red you have muddy scintillation?
(Though I realize such precision wouldn’t be possible IRL with the physical ASET setup)

video is the best way to see it.
the color zones in ASET are to wide to give a good indication.
It will show the worst ones as bad but not seperate moderate muddiness.

 

[Karl_K]

In this image of a virtual diamond in Marty type lighting you can see the crisp borders on the virtual facets.
Now if extend that crispness into 3d movement and do you have crisp scintillation? Not always because the angles have a part to play that this does not show.

 

[yssie]

I see.. and that rather answers questions 1 & 2 too

 

[Karl_K]

Here is an example of one that is a bit muddy face up.
you can see how the virtual facets are broken up and not crisp and some areas just look muddy.
Notice how many more smaller virtual facets there are.
This will often translate into muddy scintillation also.

 

[Lula]

Interesting thread!

I am not sure if this is even relevant... but my first diamond (years ago) was a gorgeous AGS-0 1.53 G/VS2. Killer diamond, truly beautiful. When I upgraded to my current (AGS-0) 2.36 J/SI2, one of the first things I noticed (besides the lovely SIZE difference!) was a difference in what I could only describe as the "crispness" of its hearts and arrows, but especially the arrows, since that's what you usually see. WHY the new stone looked *crisper* to me I never really understood, but I really liked the look. Now, the old diamond was certainly not HAZY or FUZZY in any way... in fact, I was thoroughly delighted with the H and A's when I had it. It was only when I scrutinized the stones side-by-side that I noticed the difference.

Hi, Lynn, I think your post is very relevant! I think there are a lot of us on this forum who see this "crispness" in our diamonds, but don't have the technical terms for it. But we can definitely see it with our eyes!

 

[Lula]

Here is an example of one that is a bit muddy face up.
you can see how the virtual facets are broken up and not crisp and some areas just look muddy.
Notice how many more smaller virtual facets there are.
This will often translate into muddy scintillation also.

These images are very helpful, Karl. I'm still struggling with this concept a bit, but the posts by you, Paul, and yssie have helped my understanding.

Re the images you posted:
1) Is Image #1 an H&A diamond? What about Image #2?
2) Do Image #1 and Image #2 have the same proportions (e.g., ca, pa, lgf, table, depth, etc.)?
3) From reading your posts (and Paul's) excellent crispness is due to a) cutting skill; b) the right combination of proportions -- is this correct?
4) Where does meet point symmetry fit into this discussion on crispness (if at all)?
5) Also, it is really the virtual facets that demonstrate a stone's crispness, right? So judging crispness from IS, H&A viewers, ASET, etc., is not possible? Because if crispness is seen in scintillation, we don't as yet have a way to measure scintillation (except with our eyes and with the Marty-style graphics) -- am I getting warmer?

 

[Andelain]

Karl, can you help me out a bit here, and tell me what I'm looking for in these 2 pics?

Thanks

 

[Karl_K]

Re the images you posted:
1) Is Image #1 an H&A diamond? What about Image #2? 1 is a perfect virtual diamond with perfect optical and perfect angle symmetry, the second is scan of a real diamond with so-so optical symmetry and poor angle symmetry
2) Do Image #1 and Image #2 have the same proportions (e.g., ca, pa, lgf, table, depth, etc.)? no
3) From reading your posts (and Paul's) excellent crispness is due to a) cutting skill; b) the right combination of proportions -- is this correct? it is a combination of optical symmetry, and tight angle variation with complimentary angles
4) Where does meet point symmetry fit into this discussion on crispness (if at all)? other than a diamond with id/id symetry is more likely to have decent angle variations there is none.
5) Also, it is really the virtual facets that demonstrate a stone's crispness, right? So judging crispness from IS, H&A viewers, ASET, etc., is not possible? Because if crispness is seen in scintillation, we don't as yet have a way to measure scintillation (except with our eyes and with the Marty-style graphics) -- am I getting warmer?

video is the only way to see it remotely

 

[Karl_K]

Karl, can you help me out a bit here, and tell me what I'm looking for in these 2 pics?

Thanks

Virtual facets break up light return each of the patches of color is a virtual facet.
What your looking for is uniform virtual facets with clean borders.
color doesn't matter what matters is the outline of the virtual facet and their borders.

 

[WinkHPD]

Karl, can you help me out a bit here, and tell me what I'm looking for in these 2 pics?

Thanks

Virtual facets break up light return each of the patches of color is a virtual facet.
What your looking for is uniform virtual facets with clean borders.
color doesn't matter what matters is the outline of the virtual facet and their borders.

Those photos are way interesting. Can you size them and put them both in a post so that we can see them side by side?

Wink

 

[Karl_K]

here you go

 

[WinkHPD]

Awesome. Thank you!

Wink

 

[Karl_K]

there is another side to this that sometimes does not have to do with diamond performance but has to do with seeing crisp arrow patterns.

In a diamond that is intentionally cut for h&a the angles should and are chosen so that the arrow shafts and arrow heads obstruct at about the same distances.
This will does not show up in a h&a scope, ASET or IS but is very apparent in the real world.

A diamond can have picture perfect arrows but never show them except in a very close view forcing over obstruction to darken both the shafts and heads of the arrows.

Lets take an extreme version where it does effect performance.
Here is a virtual fic that would make an awesome pendant but not so hot in ring because of over obstruction of the arrow shafts but the h&a viewer is showing perfect arrows.



The arrows in this diamond would would very rarely show as complete arrows unless it was over obstructed due to the darkness difference(amount of obstruction displayed) the heads would rarely obstruct and the shafts would obstruct too often. Yet the h&a viewer shows excellent arrows.

 

[yssie]

What sorts of proportions would make up that last type of FIC?

 

[Karl_K]

What sorts of proportions would make up that last type of FIC?

Here you go, ignore the 0 grade it would not actually get a 0 without a very long lgf%
I highlighted the problem.
It would take a 36.2 degree crown to balance out the 40.45 pavilion or a 40.6 pavilion to balance out that crown.

 

[yssie]

Thanks Karl!

This is very interesting. I had a stone w/ a 35.8avg crown (80lgf though) & 40.6avg pav and was always able to see obstruction pattern of both heads and shafts from maybe 12-15", that such small differences have visibly significant effects never ceases to surprise

 

[Lula]

Thanks again, Karl, for the great images. They demonstrate the concept of crisp optical borders very well. I guess I never realized how much of a stone's visual beauty is controlled by virtual facets, and how much slight variations in cutting can affect a stone's appearance.

I know that I can see crispness in my own diamond -- so the eyes, when trained, can make a visual assessment. But we still need to help consumers find the best stones online, sight unseen, so I'm still pushing for ways to assess a stone's potential crispness using the tools available to us as consumers. In that vein, when looking at a diamond online and trying to assess it for "crispness," would it be wise to take a look at the helium report and check on the deviations (variance) in crown, pavilion, etc.? Helium gives us a picture of how tightly the stone is cut, right? And I may be wrong, but it seems logical that a tightly cut stone would be more likely to have crisp optical borders?

Agghhh, I just feel like I'm stumbling around here, looking for the right terminology!