Perfect hearts vs Non-perfect hearts

[yssie]

In this order -

https://www.pricescope.com/journal/do_pavilion_mains_drive_light_return_modern_round_brilliant pav mains (Karl)
http://www.agslab.com/spie/spie_lo_res.pdf (detailed) AGSL intro article describing refraction & dispersion
http://www.hrdresearch.be/en/Projects/HeartsArrows/HenASub3.html The H&A guidelines, forming, and cutting sections in particular
[URL='https://www.pricescope.com/community/threads/azimuth-shift-yaw.33257/']https://www.pricescope.com/community/threads/azimuth-shift-yaw.33257/[/URL] Azimuth shift (Bruce Harding)
https://www.pricescope.com/journal/fractioning_color_gem Dispersion (Bruce Harding)

 

[yssie]

In this order -

https://www.pricescope.com/journal/do_pavilion_mains_drive_light_return_modern_round_brilliant pav mains (Karl)
http://www.agslab.com/spie/spie_lo_res.pdf (detailed) AGSL intro article describing refraction & dispersion
http://www.hrdresearch.be/en/Projects/HeartsArrows/HenASub3.html The H&A guidelines, forming, and cutting sections in particular
[URL='https://www.pricescope.com/community/threads/azimuth-shift-yaw.33257/']https://www.pricescope.com/community/threads/azimuth-shift-yaw.33257/[/URL] Azimuth shift (Bruce Harding)
https://www.pricescope.com/journal/fractioning_color_gem Dispersion (Bruce Harding)


Interesting quote -

The 'art' of cutting is basically in positioning the various facets in such a way that they optimally interact. With regards to symmetry in this exercise, there are various levels of explaining, judging and/or grading symmetry, which is extremely confusing.

1. True symmetry in positioning the facets is a factor of how well the cutters control their tools, and how dedicated they are to spend more time on getting that true symmetry. As a result, with all facets perfectly positioned, one gets a diamond without or with less 'extra' virtual facets of very small size. These 'extra' virtual facets are a negative, since they produce flashes of lower quality, not noticeable, and because they are unintended, their operation is also not directed. Furthermore, they reduce the intensity of the flash as the intended bigger virtual facet goes from 'off' to 'on' (the delta, if you wish).

2. Observed optical symmetry as in H&A-viewers is illuminating but has its limits. The viewer to start is a very simple device, separating the perimeter of a diamond basically in two colors only, and as a result, the resulting information is also a simplification in the sense that there must be lost information. There not being a standard in the design of H&A-viewers does not help either.

3. Graded optical symmetry as in H&A-grades of various labs is another story. Generally, these labs have rules to which the observed H&A-pattern should comply, meaning that if that observation passes a minimum-level, the grade is assigned.

4. Graded symmetry as in the symmetry-grade of most major labs is again something completely different. Basically here, facet junctions and other symmetry deviations are judged, with little to no attention on how the facets are positioned versus the other facets.

This difference is confusing in two ways. In a sophisticated discussion on symmetry, I might be talking about level 1 mentioned above, while others treat it as level 2, 3 or 4, leading only to misunderstanding, confusion and eventually total disagreement.

Commercially, the confusion is also high. Depending on a cutter's market, he might well be content with working at the minimum-level of level 4, 3 or 2. Definitely, worldwide, there are various markets, clearly preferring one of these levels. Level 1, with its inherent difficulty of measuring afterwards is a bit of an unknown zone, and thus not a target for most cutters.

In summary, as you can see in this thread, your question to understand and explain optical symmetry leads to a very confusing exchange, eventually ending in a division between believers and non-believers. I hope that my view, as a believer, nevertheless was somewhat illuminating.

Live long,

 

[diamond-enthusiast]

Once you look through thousands of diamonds with your unaided eyes under different lighting, it shouldn't be that tough. There's always some reason why the hearts aren't perfect.

Let's use the example teo used => http://www.goodoldgold.com/diamond/10944/

The reason for the "kink" in the hearts lies with a facet that leaks light. You can see this from the ASET image clearly. Besides other minor issues like unsymmetrical arrows also contribute to the hearts pattern seen. It shouldn't be tough to pick that up from a face up view under appropriate lighting with some experience.

I still stand by what I said earlier. Most lay people can't tell the differences. But once you reached a certain level of looking at stones, a little "unbalancing" in contrast patterns observed will tell you that the hearts and arrows isn't perfect.

Is it that important? Do you really need heats and arrows for a beautiful stone. Well, that's a subjective question. I personally kind of like it. However, nobody can answer that for you except yourself.

Can you elaborate?
Why is the "facet that leaks light" the "reason for the kink"?
Why exactly do asymmetric arrows "contribute to the hearts pattern"?
What, precisely, are the relationships between these various artifacts?
This is the sort of response that could be really interesting and educational but as it is, it's a bit wishy washy IMO - assertions alluding to examination of the nitty-gritty with no actual explanation of any of said nitty-gritty or consequences thereof. And yes, I have some thoughts, but I'll spare everyone the thousand word essay if you'll KISS it instead

Maybe I'll attempt with my rudimentary physics...

Why is the "facet that leaks light" the "reason for the kink"? The kink in the heart is a product of a facet that was not cut flatly on the plane it should occupy for optimal symmetry. As a result, light that should have been reflected off that lower facet and eventually back at the viewer is actually veering off and exiting out of a non-viewer-oriented facet ("leakage").

H&A is a phenomenon caused by reflectins of facets. Somebody had already posted the link for more details.

Why exactly do asymmetric arrows "contribute to the hearts pattern"? Hearts are the result of arrow-creating-facets (pavilion mains) being reflected off the table/crown and landing on the opposite side next to each other to create the heart images. By "contribute to the hearts pattern," I think the poster means that the asymmetric arrows (read: pavilion mains) create asymmetric hearts.

What, precisely, are the relationships between these various artifacts? Described in the previous two answers, and described here:
http://www.whiteflash.com/about-diamonds/diamond-education/how-hearts-and-arrows-diamonds.htm and discussed quite well here beginning toward the bottom of page 1: [URL='https://www.pricescope.com/community/threads/how-significant-are-the-star-facets-and-lower-girdles-info.31985/']https://www.pricescope.com/community/threads/how-significant-are-the-star-facets-and-lower-girdles-info.31985/[/URL]


Please correct me if my reasoning is off. Thank you, DE, for pointing out the connection between the ASET and the Hearts view. I'm still disoriented as to which facets are shown where in the hearts view and the arrows view, and then where light should be seen as lost as a result of deviation from optimal symmetry.

But I did want to clarify some relationships between terms. If I'm not mistaken, "optical symmetry" should really be equated with "cut symmetry" and "balance." Deviation from optimal cut symmetry is what creates unevenness in brightness along a circumferential path within a diamond (excluding intended contrast areas). Depending on the degree of facet variance, the differences in brightness might appear as hot spots, dimness or frank leakage. Because each light ray takes one path, if you have a hot spot (buildup of light rays in a spot), you'll get a dim spot somewhere else. Since hearts are the result of a symmetric cut within good proportions, perfect hearts are the byproduct of a precisely cut and well-planned diamond. With hearts, you will get balanced light return within a given proportion's potential. It's for this reason that symmetry (read: hearts) is desired.

But back to my original question: can the viewer tell the difference? Stated otherwise, can the viewer SEE these minor light imbalances in a well-proportioned diamond?

I think the answer, for most people including many vet's around here, is NO. Still, I think the craft of it is quite something.

I'm buying a HA diamond this week and will be comparing it to, what I think, is a great-looking non-HA diamond. I hope to see a difference, even if subtle (fingers crossed!). It comes with a hearts viewer, so I'll be able to make a pretty informed comparison of the two.

View it under different lighting. Most people can't but there are people who can pick out differences. Just like separating an E color from an F color diamond. How many people can see that? Not many. But there are some lay people who can. With experience, you can discern an E from an F easily too. This is the analogy that I would use.

But I did want to clarify some relationships between terms. If I'm not mistaken, "optical symmetry" should really be equated with "cut symmetry" and "balance." Deviation from optimal cut symmetry is what creates unevenness in brightness along a circumferential path within a diamond (excluding intended contrast areas). Depending on the degree of facet variance, the differences in brightness might appear as hot spots, dimness or frank leakage. Because each light ray takes one path, if you have a hot spot (buildup of light rays in a spot), you'll get a dim spot somewhere else. Since hearts are the result of a symmetric cut within good proportions, perfect hearts are the byproduct of a precisely cut and well-planned diamond. With hearts, you will get balanced light return within a given proportion's potential. It's for this reason that symmetry (read: hearts) is desired.

But back to my original question: can the viewer tell the difference? Stated otherwise, can the viewer SEE these minor light imbalances in a well-proportioned diamond?

You are trying to differentiate between an A+ grade and an A grade. The differences are subtle.

Most lay people can't see differences without critically examining the stone under different lighting for near perfect H&A.

Stated otherwise, can the viewer SEE these minor light imbalances in a well-proportioned diamond?
I would limit my answers to well proportioned diamond with good optical symmetry. Most people can't. Again, everybody's tolerance and eye for details is different.

 

[Christina...]

Once you look through thousands of diamonds with your unaided eyes under different lighting, it shouldn't be that tough. There's always some reason why the hearts aren't perfect.

Let's use the example teo used => http://www.goodoldgold.com/diamond/10944/

The reason for the "kink" in the hearts lies with a facet that leaks light. You can see this from the ASET image clearly. Besides other minor issues like unsymmetrical arrows also contribute to the hearts pattern seen. It shouldn't be tough to pick that up from a face up view under appropriate lighting with some experience.

I still stand by what I said earlier. Most lay people can't tell the differences. But once you reached a certain level of looking at stones, a little "unbalancing" in contrast patterns observed will tell you that the hearts and arrows isn't perfect.

Is it that important? Do you really need heats and arrows for a beautiful stone. Well, that's a subjective question. I personally kind of like it. However, nobody can answer that for you except yourself.

Can you elaborate?
Why is the "facet that leaks light" the "reason for the kink"?
Why exactly do asymmetric arrows "contribute to the hearts pattern"?
What, precisely, are the relationships between these various artifacts?
This is the sort of response that could be really interesting and educational but as it is, it's a bit wishy washy IMO - assertions alluding to examination of the nitty-gritty with no actual explanation of any of said nitty-gritty or consequences thereof. And yes, I have some thoughts, but I'll spare everyone the thousand word essay if you'll KISS it instead

Maybe I'll attempt with my rudimentary physics...

Why is the "facet that leaks light" the "reason for the kink"? The kink in the heart is a product of a facet that was not cut flatly on the plane it should occupy for optimal symmetry. As a result, light that should have been reflected off that lower facet and eventually back at the viewer is actually veering off and exiting out of a non-viewer-oriented facet ("leakage").

H&A is a phenomenon caused by reflectins of facets. Somebody had already posted the link for more details.

Why exactly do asymmetric arrows "contribute to the hearts pattern"? Hearts are the result of arrow-creating-facets (pavilion mains) being reflected off the table/crown and landing on the opposite side next to each other to create the heart images. By "contribute to the hearts pattern," I think the poster means that the asymmetric arrows (read: pavilion mains) create asymmetric hearts.

What, precisely, are the relationships between these various artifacts? Described in the previous two answers, and described here:
http://www.whiteflash.com/about-diamonds/diamond-education/how-hearts-and-arrows-diamonds.htm and discussed quite well here beginning toward the bottom of page 1: [URL='https://www.pricescope.com/community/threads/how-significant-are-the-star-facets-and-lower-girdles-info.31985/']https://www.pricescope.com/community/threads/how-significant-are-the-star-facets-and-lower-girdles-info.31985/[/URL]


Please correct me if my reasoning is off. Thank you, DE, for pointing out the connection between the ASET and the Hearts view. I'm still disoriented as to which facets are shown where in the hearts view and the arrows view, and then where light should be seen as lost as a result of deviation from optimal symmetry.

But I did want to clarify some relationships between terms. If I'm not mistaken, "optical symmetry" should really be equated with "cut symmetry" and "balance." Deviation from optimal cut symmetry is what creates unevenness in brightness along a circumferential path within a diamond (excluding intended contrast areas). Depending on the degree of facet variance, the differences in brightness might appear as hot spots, dimness or frank leakage. Because each light ray takes one path, if you have a hot spot (buildup of light rays in a spot), you'll get a dim spot somewhere else. Since hearts are the result of a symmetric cut within good proportions, perfect hearts are the byproduct of a precisely cut and well-planned diamond. With hearts, you will get balanced light return within a given proportion's potential. It's for this reason that symmetry (read: hearts) is desired.

But back to my original question: can the viewer tell the difference? Stated otherwise, can the viewer SEE these minor light imbalances in a well-proportioned diamond?

I think the answer, for most people including many vet's around here, is NO. Still, I think the craft of it is quite something.

I'm buying a HA diamond this week and will be comparing it to, what I think, is a great-looking non-HA diamond. I hope to see a difference, even if subtle (fingers crossed!). It comes with a hearts viewer, so I'll be able to make a pretty informed comparison of the two.

View it under different lighting. Most people can't but there are people who can pick out differences. Just like separating an E color from an F color diamond. How many people can see that? Not many. But there are some lay people who can. With experience, you can discern an E from an F easily too. This is the analogy that I would use.

But I did want to clarify some relationships between terms. If I'm not mistaken, "optical symmetry" should really be equated with "cut symmetry" and "balance." Deviation from optimal cut symmetry is what creates unevenness in brightness along a circumferential path within a diamond (excluding intended contrast areas). Depending on the degree of facet variance, the differences in brightness might appear as hot spots, dimness or frank leakage. Because each light ray takes one path, if you have a hot spot (buildup of light rays in a spot), you'll get a dim spot somewhere else. Since hearts are the result of a symmetric cut within good proportions, perfect hearts are the byproduct of a precisely cut and well-planned diamond. With hearts, you will get balanced light return within a given proportion's potential. It's for this reason that symmetry (read: hearts) is desired.

But back to my original question: can the viewer tell the difference? Stated otherwise, can the viewer SEE these minor light imbalances in a well-proportioned diamond?

You are trying to differentiate between an A+ grade and an A grade. The differences are subtle.

Most lay people can't see differences without critically examining the stone under different lighting for near perfect H&A.

Stated otherwise, can the viewer SEE these minor light imbalances in a well-proportioned diamond?
I would limit my answers to well proportioned diamond with good optical symmetry. Most people can't. Again, everybody's tolerance and eye for details is different.

If the OPs original question had been 'Can we see a difference from a GIA EX stone and a TRUE HA?', then I would mostly agree with the bolded, however since we are talking about NEAR perfect hearts and perfect hearts, both arguably cut with careful planning and tight variances, then I would still argue that though tiny nuances may be seen through certain scientific instruments they would NOT be discernible by the unaided human eye regardless of viewing environment.

 

[diamond-enthusiast]

This shall be my last post in this thread. I tire of people consistently missing the point here instead of taking time to read.

For the 4th time I'm repeating myself; most people cannot tell the differences in near H&A or perfect H&A diamonds. I don't see why people keep harping on this when they in fact agree with this statement.

Teo, you listed examples from good old gold. Why don't you contact them to make a video of all three to see it for yourself. That's the best way to answer a subjective question that can never be answered by reading peoples' opinion.

While the best learning comes from viewing physical stones, you can probably dig through tons of Youtube videos to see comparisons yourself for a start. Here's a supposedly superior diamond against a premium diamond video from GOG. You had listed similar stones in your first post.

http://www.youtube.com/watch?v=uxVfKUJsRZY

Since you have the luxury of examining stones in person, that's great. Based on your post, you are worried about light performance. If you don't see any differences between 2 diamonds optically, it makes sense to buy the cheaper one doesn't it?

edited to clarify reply*