True Hearts - Technical discussion

[Garry H (Cut Nut)]

There was a thread titled True Hearts?????? is this stone a true heart? here https://www.pricescope.com/community/threads/true-hearts-is-this-stone-a-true-heart.90360/ which Admin closed because they thought it was a bit off the consumers request for info / topic.

Some people thought the topic was gradually getting somewhere, and given that HRD has just established a grading system for H&A''s and there has been debate about the linkage between cut quality and the role of H&A''s and clefts in hearst etc - Andrey is very happy to link these two threads and the nerds can discuss and debate these issues here.

so, on the count of 3.......1,.....2,.......

 

[Serg]

Date: 7/28/2008 4:54:01 PM
Author:Garry H (Cut Nut)
There was a thread titled True Hearts?????? is this stone a true heart? here https://www.pricescope.com/community/threads/true-hearts-is-this-stone-a-true-heart.90360/ which Admin closed because they thought it was a bit off the consumers request for info / topic.

Some people thought the topic was gradually getting somewhere, and given that HRD has just established a grading system for H&A''s and there has been debate about the linkage between cut quality and the role of H&A''s and clefts in hearst etc - Andrey is very happy to link these two threads and the nerds can discuss and debate these issues here.

so, on the count of 3.......1,.....2,.......

re:which Admin closed because they thought it was a bit off the consumers request for info / topic.

It is not reason to close thread. At least such rule is absent in PS policy

re:Andrey is very happy to link these two threads and the nerds can discuss and debate these issues here.

And then Andrew or somebody will think again something and Andrew will close thread again

Thanks , I do not like play in game when Admin do not follow open rules

I prefer know REAL reason, why Andrew closed nice thread before I will give any technical input on PS again

 

[adamasgem]

Well, after reading about three pages of the other thread, it appeared that NO ONE brought up the fact that the photographed H&A image is strongly dependent on the size of the stone with respect to the size of the "H&A Viewer".

Which means that a one carat and a two carat stone, IDENTICALLY CUT, will have two DIFFERENT H&A images.


Comments?

 

[agc]

Garry I am waiting for the full unveiling of HRD grading of H&A''s. From the bits and pieces of this grading that I have seen, I find it interesting that clefts in the hearts do not automatically result in failure but instead are given degrees of penalty. Likewise they give degrees of penalty for unbalanced V''s which current proponents of true H&A''s seem to neglect. I have never seen the document describing the Japanese criteria for H&A''s but apparantly it does not fail variable V''s. It has been my contention that I would prefer a diamond with symmetrical clefted hearts (due to longer lgf) AND symmetical V''s than a "true" H&A with symmetrical closed hearts AND variable V''s. I feel the clefted heart (solely due to longer lgf) diamond example above could have superior optical symmetry since hearts and V''s are symmetrical while the closed heart example is not as optically precise due to only the hearts being symmetric and the V''s variable (azimuth shift/yaw). It looks like HRD will start to penalize some of these true H&A and not automatically fail all hearts with clefts.

 

[strmrdr]

Date: 7/28/2008 6:34:01 PM
Author: adamasgem
Well, after reading about three pages of the other thread, it appeared that NO ONE brought up the fact that the photographed H&A image is strongly dependent on the size of the stone with respect to the size of the 'H&A Viewer'.


Which means that a one carat and a two carat stone, IDENTICALLY CUT, will have two DIFFERENT H&A images.



Comments?

true as well as under different scopes.
I have compared the same stone under 3 different H&A scopes side by side and there was a wide range in the image appearance under them.
..........

I'm out too, anything beyond look at the pretty picture for the sake of pretty pictures clearly wasn't welcome.

 

[Garry H (Cut Nut)]

Date: 7/28/2008 6:40:08 PM
Author: agc
Garry I am waiting for the full unveiling of HRD grading of H&A''s. From the bits and pieces of this grading that I have seen, I find it interesting that clefts in the hearts do not automatically result in failure but instead are given degrees of penalty. Likewise they give degrees of penalty for unbalanced V''s which current proponents of true H&A''s seem to neglect. I have never seen the document describing the Japanese criteria for H&A''s but apparantly it does not fail variable V''s. It has been my contention that I would prefer a diamond with symmetrical clefted hearts (due to longer lgf) AND symmetical V''s than a ''true'' H&A with symmetrical closed hearts AND variable V''s. I feel the clefted heart (solely due to longer lgf) diamond example above could have superior optical symmetry since hearts and V''s are symmetrical while the closed heart example is not as optically precise due to only the hearts being symmetric and the V''s variable (azimuth shift/yaw). It looks like HRD will start to penalize some of these true H&A and not automatically fail all hearts with clefts.

AGC I am sure someone can give a link to the japanese page.

Here is some data from the CiamCalc Pro on the default 57% tolkowsky stone with different gridle depths:

The 85% deep lgf have
ETAS Fire Simple stereo 0.97849
ETAS Fire Intensity weighted stereo 1.05207
ETAS Fire Intensity and Square weighted stereo 1.00084
ETAS Dynamic (only Mono) Simple mono 1.00914
ETAS Dynamic (only Mono) Intensity weighted mono 1.04027
And the 80% deep lgf have
ETAS Fire Simple stereo 1.02036
ETAS Fire Intensity weighted stereo 1.03406
ETAS Fire Intensity and Square weighted stereo 1.05484
ETAS Dynamic (only Mono) Simple mono 1.15393
ETAS Dynamic (only Mono) Intensity weighted mono 1.05667

Others can run light return data, but only a few of have this pro version of DC
What is shown above indicates that the potential to see fire and scintillation is greater in the 80% stone than in an 85% deep lgf.
I should qualify that this is not a “grading system” per se’, but data from a respected source.
Others may wish to run the same stones thru PGS for a separate opinion.

 

[strmrdr]

Date: 7/28/2008 8:42:58 PM
Author: Garry H (Cut Nut)

Date: 7/28/2008 6:40:08 PM

Author: agc

Garry I am waiting for the full unveiling of HRD grading of H&A''s. From the bits and pieces of this grading that I have seen, I find it interesting that clefts in the hearts do not automatically result in failure but instead are given degrees of penalty. Likewise they give degrees of penalty for unbalanced V''s which current proponents of true H&A''s seem to neglect. I have never seen the document describing the Japanese criteria for H&A''s but apparantly it does not fail variable V''s. It has been my contention that I would prefer a diamond with symmetrical clefted hearts (due to longer lgf) AND symmetical V''s than a ''true'' H&A with symmetrical closed hearts AND variable V''s. I feel the clefted heart (solely due to longer lgf) diamond example above could have superior optical symmetry since hearts and V''s are symmetrical while the closed heart example is not as optically precise due to only the hearts being symmetric and the V''s variable (azimuth shift/yaw). It looks like HRD will start to penalize some of these true H&A and not automatically fail all hearts with clefts.

AGC I am sure someone can give a link to the japanese page.


Here is some data from the CiamCalc Pro on the default 57% tolkowsky stone with different gridle depths:


The 85% deep lgf have

ETAS Fire Simple stereo 0.97849

ETAS Fire Intensity weighted stereo 1.05207

ETAS Fire Intensity and Square weighted stereo 1.00084

ETAS Dynamic (only Mono) Simple mono 1.00914

ETAS Dynamic (only Mono) Intensity weighted mono 1.04027

And the 80% deep lgf have

ETAS Fire Simple stereo 1.02036

ETAS Fire Intensity weighted stereo 1.03406

ETAS Fire Intensity and Square weighted stereo 1.05484

ETAS Dynamic (only Mono) Simple mono 1.15393

ETAS Dynamic (only Mono) Intensity weighted mono 1.05667


Others can run light return data, but only a few of have this pro version of DC

What is shown above indicates that the potential to see fire and scintillation is greater in the 80% stone than in an 85% deep lgf.

I should qualify that this is not a “grading system” per se’, but data from a respected source.

Others may wish to run the same stones thru PGS for a separate opinion.

finally something interesting.
For the default tolk and similar stones I will grant that around 80 is the right lgf% BUT to apply that to other combinations is not correct.
I showed that in the other thread.

 

[adamasgem]

Date: 7/28/2008 8:13:15 PM
Author: strmrdr

Date: 7/28/2008 6:34:01 PM
Author: adamasgem
Well, after reading about three pages of the other thread, it appeared that NO ONE brought up the fact that the photographed H&A image is strongly dependent on the size of the stone with respect to the size of the ''H&A Viewer''.


Which means that a one carat and a two carat stone, IDENTICALLY CUT, will have two DIFFERENT H&A images.



Comments?

true as well as under different scopes.
I have compared the same stone under 3 different H&A scopes side by side and there was a wide range in the image appearance under them.
..........

I''m out too, anything beyond look at the pretty picture for the sake of pretty pictures clearly wasn''t welcome.

The diameter of the scope and the height of the colored contrast area control the image.
Centering is more a problem in the table down position (Hearts)

Big question, what are the size parameters (diameter of stone) and reference H&A design. D we go back to the original patent.

 

[agc]

Date: 7/28/2008 8:50:17 PM
Author: strmrdr

Date: 7/28/2008 8:42:58 PM
Author: Garry H (Cut Nut)

Date: 7/28/2008 6:40:08 PM

Author: agc

Garry I am waiting for the full unveiling of HRD grading of H&A''s. From the bits and pieces of this grading that I have seen, I find it interesting that clefts in the hearts do not automatically result in failure but instead are given degrees of penalty. Likewise they give degrees of penalty for unbalanced V''s which current proponents of true H&A''s seem to neglect. I have never seen the document describing the Japanese criteria for H&A''s but apparantly it does not fail variable V''s. It has been my contention that I would prefer a diamond with symmetrical clefted hearts (due to longer lgf) AND symmetical V''s than a ''true'' H&A with symmetrical closed hearts AND variable V''s. I feel the clefted heart (solely due to longer lgf) diamond example above could have superior optical symmetry since hearts and V''s are symmetrical while the closed heart example is not as optically precise due to only the hearts being symmetric and the V''s variable (azimuth shift/yaw). It looks like HRD will start to penalize some of these true H&A and not automatically fail all hearts with clefts.

AGC I am sure someone can give a link to the japanese page.


Here is some data from the CiamCalc Pro on the default 57% tolkowsky stone with different gridle depths:


The 85% deep lgf have

ETAS Fire Simple stereo 0.97849

ETAS Fire Intensity weighted stereo 1.05207

ETAS Fire Intensity and Square weighted stereo 1.00084

ETAS Dynamic (only Mono) Simple mono 1.00914

ETAS Dynamic (only Mono) Intensity weighted mono 1.04027


And the 80% deep lgf have

ETAS Fire Simple stereo 1.02036

ETAS Fire Intensity weighted stereo 1.03406

ETAS Fire Intensity and Square weighted stereo 1.05484

ETAS Dynamic (only Mono) Simple mono 1.15393

ETAS Dynamic (only Mono) Intensity weighted mono 1.05667


Others can run light return data, but only a few of have this pro version of DC

What is shown above indicates that the potential to see fire and scintillation is greater in the 80% stone than in an 85% deep lgf.

I should qualify that this is not a “grading system” per se’, but data from a respected source.

Others may wish to run the same stones thru PGS for a separate opinion.

finally something interesting.
For the default tolk and similar stones I will grant that around 80 is the right lgf% BUT to apply that to other combinations is not correct.
I showed that in the other thread.

For a tolkowsky stone I can see how 80% lgf would be better but the current H&A grading system automatically fails even an 80% lgf regardless of the ca/pa combo.

 

[strmrdr]

Date: 7/28/2008 9:26:46 PM
Author: agc

Date: 7/28/2008 8:50:17 PM




For a tolkowsky stone I can see how 80% lgf would be better but the current H&A grading system automatically fails even an 80% lgf regardless of the ca/pa combo.

yep that''s why the current "true h&a" system is wrong.

 

[purrfectpear]

Date: 7/28/2008 9:42:43 PM
Author: strmrdr

Date: 7/28/2008 9:26:46 PM
Author: agc

Date: 7/28/2008 8:50:17 PM




For a tolkowsky stone I can see how 80% lgf would be better but the current H&A grading system automatically fails even an 80% lgf regardless of the ca/pa combo.

yep that''s why the current ''true h&a'' system is wrong.

Wrong, or just biased?

 

[strmrdr]

Date: 7/28/2008 9:52:44 PM
Author: purrfectpear

Date: 7/28/2008 9:42:43 PM

Author: strmrdr

Date: 7/28/2008 9:26:46 PM

Author: agc

Date: 7/28/2008 8:50:17 PM





For a tolkowsky stone I can see how 80% lgf would be better but the current H&A grading system automatically fails even an 80% lgf regardless of the ca/pa combo.

yep that''s why the current ''true h&a'' system is wrong.

Wrong, or just biased?

both, there has been a strong bias towards tolk and tolk like diamonds in recent years as the move away from 60/60 was made.
Garry with his hca was a cry in the wilderness then the new AGS system came along and proved him right.

The AGS system will move a diamond out of 0 for the wrong lgf%.

While the AGS system is good it is far from the ultimate as there are many questions left to be answered.
In 5 to 10 years we will look back at today''s systems and say... what were we thinking?
Much as people look back at the old AGS system today.
Then in 15-20 years people will look back at that system and say the same.

 

[John P]

Date: 7/28/2008 8:50:17 PM
Author: strmrdr

finally something interesting.
For the default tolk and similar stones I will grant that around 80 is the right lgf% BUT to apply that to other combinations is not correct.
I showed that in the other thread.

Strm I've had the numbers Garry posted here for some time but didn't put them in the other thread because I was avoiding the X is better than Y performance horse you're beating. I (still) feel it's a separate topic from whether a pattern looks like a heart or a duck or a smiling bunny in a viewer.

Marty's first comment here only reinforces that to me (by the way, HRD released specs for a standardized viewer).

Date: 7/28/2008 9:26:46 PM
Author: agc
For a tolkowsky stone I can see how 80% lgf would be better but the current H&A grading system automatically fails even an 80% lgf regardless of the ca/pa combo.

PSA: Garry used lower facet depth% rather than height% to generate the figures (height appears on grading reports and is what we more commonly use in discussions here). So 85 and 80 are actually 83.8% and 78.4% relative to prior discussions.

 

[adamasgem]

Date: 7/29/2008 11:58:48 AM
Author: John Pollard

Strm I''ve had the numbers Garry posted here for some time but didn''t put them in the other thread because I was avoiding the X is better than Y performance horse you''re beating. I (still) feel it''s a separate topic from whether a pattern looks like a heart or a duck or a smiling bunny in a viewer.

Marty''s first comment here only reinforces that to me (by the way, HRD released specs for a standardized viewer).

John: Can you send me the HRD specs...

BTW Here is a way out comparison of a 6mm and a 26mm identical cut done with DiamondCalc, which says to me that DC has a fixed size viewer model currently.

Since the stones are identical except for SIZE, their theoretical NON ABSORBING PERFORMANCE characteristics and metrics would (should) be the same.

Fixed size contrast viewers are great for assessing symmetry, NOTHING ELSE, PERIOD, end of marketing hype, unless one is comparing stones of some "reference" diameter.

Now given the scanner accuracy, how well can one really rely on how close the "Vs" are to the hearts, even in a rendering ? (If I have the nomenclature correct)

 

[Garry H (Cut Nut)]

It is fixed in the latest DiamCalc Marty, but in the real world it is true.

 

[adamasgem]

Date: 7/30/2008 4:40:01 PM
Author: Garry H (Cut Nut)
It is fixed in the latest DiamCalc Marty, but in the real world it is true.

What is fixed and what is the baseline definition according to whom. I have HASP 3.0.
Fixed viewer or fixed angles of incidence of colored light? Maybe should be both available..

Fixed angles of incidence (variable sized viewer) makes more sense from a relative performance standpoint, if one wants to argue about LGFs etc.

 

[adamasgem]

Date: 7/30/2008 4:40:01 PM
Author: Garry H (Cut Nut)
It is fixed in the latest DiamCalc Marty, but in the real world it is true.

SHould all H&A viewers come with a permanent printed consumer warning label

H&A INTERPRETATION RESULTS INVALID, EXCEPT ON A 1.0ct(?) RBC

 

[Garry H (Cut Nut)]

Date: 7/30/2008 5:10:02 PM
Author: adamasgem

Date: 7/30/2008 4:40:01 PM
Author: Garry H (Cut Nut)
It is fixed in the latest DiamCalc Marty, but in the real world it is true.

What is fixed and what is the baseline definition according to whom. I have HASP 3.0.
Fixed viewer or fixed angles of incidence of colored light? Maybe should be both available..

Fixed angles of incidence (variable sized viewer) makes more sense from a relative performance standpoint, if one wants to argue about LGFs etc.

Strange Marty, the lighting structures are the same under ''adavnced'' lighting config - but the images are different - the size makes very little change to the hearts, more change t the arrows colour though.
Hopefully Sergey can come and explain, but he is meant to be on vacation

 

[Garry H (Cut Nut)]

Date: 7/30/2008 5:24:31 PM
Author: adamasgem

Date: 7/30/2008 4:40:01 PM
Author: Garry H (Cut Nut)
It is fixed in the latest DiamCalc Marty, but in the real world it is true.

SHould all H&A viewers come with a permanent printed consumer warning label

H&A INTERPRETATION RESULTS INVALID, EXCEPT ON A 1.0ct(?) RBC

I had the same complaint and request re ideal-scope design from an associate who made +6ct average goods.

 

[adamasgem]

Date: 7/30/2008 5:34:15 PM
Author: Garry H (Cut Nut)

Date: 7/30/2008 5:10:02 PM
Author: adamasgem

Date: 7/30/2008 4:40:01 PM
Author: Garry H (Cut Nut)
It is fixed in the latest DiamCalc Marty, but in the real world it is true.

What is fixed and what is the baseline definition according to whom. I have HASP 3.0.
Fixed viewer or fixed angles of incidence of colored light? Maybe should be both available..

Fixed angles of incidence (variable sized viewer) makes more sense from a relative performance standpoint, if one wants to argue about LGFs etc.

Strange Marty, the lighting structures are the same under ''adavnced'' lighting config - but the images are different - the size makes very little change to the hearts, more change t the arrows colour though.
Hopefully Sergey can come and explain, but he is meant to be on vacation

I think the white hearts result from a very narrow angular range of very high angle lighting.

 

[Garry H (Cut Nut)]

Date: 7/30/2008 5:10:02 PM
Author: adamasgem

Date: 7/30/2008 4:40:01 PM
Author: Garry H (Cut Nut)
It is fixed in the latest DiamCalc Marty, but in the real world it is true.

What is fixed and what is the baseline definition according to whom. I have HASP 3.0.
Fixed viewer or fixed angles of incidence of colored light? Maybe should be both available..

Fixed angles of incidence (variable sized viewer) makes more sense from a relative performance standpoint, if one wants to argue about LGFs etc.

Marty need an opinion from Sergey - but I suspect the answer is to modl a really big 5M high scope.

The changes in the older version and the beta I am testing do not appear to be showing up in the appropriate screens?????

 

[adamasgem]

Date: 7/30/2008 11:39:40 PM
Author: Garry H (Cut Nut)

Date: 7/30/2008 5:10:02 PM
Author: adamasgem

Date: 7/30/2008 4:40:01 PM
Author: Garry H (Cut Nut)
It is fixed in the latest DiamCalc Marty, but in the real world it is true.

What is fixed and what is the baseline definition according to whom. I have HASP 3.0.
Fixed viewer or fixed angles of incidence of colored light? Maybe should be both available..

Fixed angles of incidence (variable sized viewer) makes more sense from a relative performance standpoint, if one wants to argue about LGFs etc.

Marty need an opinion from Sergey - but I suspect the answer is to modl a really big 5M high scope.

The changes in the older version and the beta I am testing do not appear to be showing up in the appropriate screens?????

Sergey should have an opion for fixed size viewer or fixed angular, so one could visualize what they would see in their viewers...

Metrics are only meaningfull for fixed angles...IMO

Good discussion.. glad it got off the private emails..
If it confuses the sellers or consumers, let them learn...

The other thing I'd like to see is an offset viewer model simulation, so consumers can learn how they can be mis-lead if the stone isn't perfectly centered..

I guess I could kludge a Sarin file to show the effect by offsetting each x coordinate..

 

[Serg]

Date: 7/30/2008 5:34:15 PM
Author: Garry H (Cut Nut)

Date: 7/30/2008 5:10:02 PM
Author: adamasgem

Date: 7/30/2008 4:40:01 PM
Author: Garry H (Cut Nut)
It is fixed in the latest DiamCalc Marty, but in the real world it is true.

What is fixed and what is the baseline definition according to whom. I have HASP 3.0.
Fixed viewer or fixed angles of incidence of colored light? Maybe should be both available..

Fixed angles of incidence (variable sized viewer) makes more sense from a relative performance standpoint, if one wants to argue about LGFs etc.

Strange Marty, the lighting structures are the same under ''adavnced'' lighting config - but the images are different - the size makes very little change to the hearts, more change t the arrows colour though.
Hopefully Sergey can come and explain, but he is meant to be on vacation

Garry,
You work in new HDR mode. Just turn on HDR mode( new button on left side) and you will receive same image like Marty
HDR mode does support yet only beams( rays going out from diamond) from center coordinate ( diamond has zero size )
HDR mode has advantages for visualization , But old mode is more optically correct. We use only old mode for research and metrics .
HDR mode we use for nice visualization only ( Stars, Bloom,..)
Sorry, what I did not inform you early

 

[Rhino]

Ok… Sorry for my delay in responding all. Whenever we return from vacation we do so to quite a bit of work. I’m sorry to see our original thread closed so I will respond here.

Firstly, thank you Brian, John, Wink, Allison, Garry, Serg and all the other PS’rs who contributed in the other thread.

One reason I replied in the original thread is because I find myself often answering this same question over and over again via email. Ie. How does this diamond fail in optical precision/perfection?

While the distinguished subjects of Optical Symmetry and Light Performance were properly addressed (and rightly so) it is strm, agc and jasontb who hit the nail on the head.

To quote jasontb on page 6 …

*BUT* the presence or lack of a cleft in the heart has nothing to do with the amount of symmetry or precision in the stone. And it is no harder to make a stone with perfect hearts versus an identical stone with cleft hearts. It is just a matter of angles and measurements selected by the cutter.

My point is being proven over and over again. People think a cleft heart is somehow indicative of inferior craftsmanship.

To quote agc “

Date: 7/20/2008 12:07:16 PM
Author: agc
My two cents on the issue. Marketing forces (not on this forum) have sold the general public the line that H&A are the ultimate, best cut, best performing diamonds and anything less is second best. When the average consumer comes to this forum and reads a tutorial on H&A and sees that the hearts with clefts ''FAILS'' many automatically assume that means less precision, less perfect and less beauty since it ''FAILED''. Most do not realize this is strictly a patterning issue and not a direct measure of performance. They do not understand that diamonds with longer lgf will have clefts and could actually be cut tighter and perform better than a true, traditional H&A and therefore are not ''FAILURES'' of quality or performance. It all comes down to perception of the word ''FAIL''. IMHO.

Also from agc…

Except for the fact that many proponents of H&A''s point out their finest (ultimate) optical symmetry status while not disclosing to the consumer that non H&A can also be finest (ultimate) but they are quick to label the non H&A with the "FAILED H&A" leaving the consumer feeling non H&A are inferior even though they did not come right out and say that. It is implied but has deniability.

Again agc and perhaps most importantly …

One more thought as I went back to look at the H&A tutorial. The first lines start out with this.
You already learned that cut is the most important factor affecting the beauty of a diamond.
The aim of this tutorial is to illustrate what it takes to achieve the ultimate in cutting precision and perfection - super ideal cut Hearts and Arrows diamonds.

As agc has pointed out … if the aim of the tutorial is to illustrate what it takes to achieve the ultimate in cutting precision and perfection, it is misleading consumers to believe that perfect optical symmetry and cutting perfection can only be accomplished by the observance of only one particular type of optical symmetry pattern (ie. That produced by 75-78% lower halves) and everything else fails.
Every knowledgeable person on the subject (gemologist and layman) disagrees. Perfection & precision of cut can be identified by more than one optically symmetrical pattern and in no way is limited to 75-78% lower halves. To suggest otherwise is misleading information. I carry various types of precision cut diamonds that produce different optical patterns and I can show you diamonds with open hearts cut with much greater precision than some with closed hearts.

My .02c

Peace,
Jonathan

 

[WinkHPD]

Date: 8/1/2008 6:41:48 PM
Author: Rhino

One more thought as I went back to look at the H&A tutorial. The first lines start out with this.
You already learned that cut is the most important factor affecting the beauty of a diamond.
The aim of this tutorial is to illustrate what it takes to achieve the ultimate in cutting precision and perfection - super ideal cut Hearts and Arrows diamonds.

As agc has pointed out … if the aim of the tutorial is to illustrate what it takes to achieve the ultimate in cutting precision and perfection, it is misleading consumers to believe that perfect optical symmetry and cutting perfection can only be accomplished by the observance of only one particular type of optical symmetry pattern (ie. That produced by 75-78% lower halves) and everything else fails.
Every knowledgeable person on the subject (gemologist and layman) disagrees. Perfection & precision of cut can be identified by more than one optically symmetrical pattern and in no way is limited to 75-78% lower halves. To suggest otherwise is misleading information. I carry various types of precision cut diamonds that produce different optical patterns and I can show you diamonds with open hearts cut with much greater precision than some with closed hearts.

My .02c

Peace,
Jonathan

It depends on how I read this whether I disagree or not.

If you are saying everyone agrees that hearts and arrows are only created by lower girdle halves of 75 - 78% then I not only disagree but I wonder where you got those numbers. I do not remember the bottom number, but am pretty sure the top length of H&A is 80%.

If you are saying that anything outside the correct length of lower girdle facets fails, then I absolutely agree NOT DISAGREE, They do fail to be H&A. This would be agreed on by the vendors of the H&A diamonds, the cutters of H&A diamonds, and the Japanese Laboratories and HRD who grade for the patterns of the H&A diamonds. That you have established that other patterns also have wonderful light performance and optical symmetry is wonderful and true, but it does NOT MAKE THEM H&A.

If you are saying that optical symmetry and top light performance can be garnered by other patterns than H&A, then I absolutely agree with you. I said the same thing in the other thread and you said I miss your point.

If your point is that you can call anything you want H&A, then I am not missing your point, just strongly disagreeing with it. There are and have been recognized standards since the Japanese Labs graded for H&A long before we started selling them in this country.

I continue to agree with Paul that we should not call them H&A but rather symmetry and contrast patterns, which would alleviate your problems with wanting to call your very long lower girdle facets with the clefted hearts H&A, which they are not. I furrther agree with John Pollard that we need to call them something other than symmetry patterns to avoid confusing the public, who are already confused by the difference in physical symmetry and optical symmetry without us adding a third kind of symmetry.

Wink

 

[John P]

Hi Rhino,

It might help to separate the two different topics that are tangled here; patterning and performance.

TOPIC 1 - PATTERNING (aka shapes, aka geometry) - this is what the PS tutorial is about.

Question: Which shape, seen in the reflective H&A viewer, shows the pattern (geometric shape) that the PS tutorial and gemological bodies from the original Japanese labs to EGL, IGI, WGI and now HRD (all of the major labs grading H&A) consider "Hearts?"

The answer is B.

All of the gemological bodies I listed above agree. There is no debate. It is a topic separate from optical performance.

TOPIC 2 - PERFORMANCE (aka optics, aka beauty) - this is a different subject, and the one you're speaking of.

Question: True or false - Diamonds showing any of the above patterns can be beautiful and perform equally well?

The answer is TRUE.

Again, there is no debate. Eightstar produces amazing rounds with lower halves too short to look like traditional hearts patterns (they resemble letter C above) - they don't fall into the classification we call H&A. No problem. They're beautiful and no one says differently. Other diamonds have lower halves too long to show traditional hearts patterns (they can resemble letter A above). Again, they can be stunning and no one debates that.

Performance is a different topic than whether the diamond falls into the traditional H&A classification.

The Pricescope “Hearts & Arrows” tutorial is perfectly titled: It shows how to create the traditional HEART SHAPED patterns in the pavilion of a round. It is not judging performance.

One must know a diamond's light return to know how well it performs. We professionals remind consumers of that all the time. So let’s remind ourselves of it now.

 

[John P]

Date: 8/1/2008 7:10:19 PM
Author: Wink

I continue to agree with Paul that we should not call them H&A but rather symmetry and contrast patterns, which would alleviate your problems with wanting to call your very long lower girdle facets with the clefted hearts H&A, which they are not. I furrther agree with John Pollard that we need to call them something other than symmetry patterns to avoid confusing the public, who are already confused by the difference in physical symmetry and optical symmetry without us adding a third kind of symmetry.

Wink

Thanks Wink. Actually our company shows images of our princess cuts taken in a "H&A" viewer to demonstrate cut precision. In fact, we even call the images "Hearts" and "Arrows" photos because the traditional viewer (developed to see those patterns) is known by that name everywhere in the world. We explain to clients that our princess cuts are not going to show "hearts" in the pavilion (just as Rhino's diamonds will not) because it's not cut in the traditional H&A round configuration.

I would be all for re-naming H&A views as "precision & contrast" views - easier for all makes - but it would not change the definition of what fits into the traditional H&A classification as it is known.

 

[agc]

Date: 8/1/2008 7:10:19 PM
Author: Wink

Date: 8/1/2008 6:41:48 PM
Author: Rhino



One more thought as I went back to look at the H&A tutorial. The first lines start out with this.
You already learned that cut is the most important factor affecting the beauty of a diamond.
The aim of this tutorial is to illustrate what it takes to achieve the ultimate in cutting precision and perfection - super ideal cut Hearts and Arrows diamonds.

As agc has pointed out … if the aim of the tutorial is to illustrate what it takes to achieve the ultimate in cutting precision and perfection, it is misleading consumers to believe that perfect optical symmetry and cutting perfection can only be accomplished by the observance of only one particular type of optical symmetry pattern (ie. That produced by 75-78% lower halves) and everything else fails.
Every knowledgeable person on the subject (gemologist and layman) disagrees. Perfection & precision of cut can be identified by more than one optically symmetrical pattern and in no way is limited to 75-78% lower halves. To suggest otherwise is misleading information. I carry various types of precision cut diamonds that produce different optical patterns and I can show you diamonds with open hearts cut with much greater precision than some with closed hearts.

My .02c

Peace,
Jonathan

It depends on how I read this whether I disagree or not.

If you are saying everyone agrees that hearts and arrows are only created by lower girdle halves of 75 - 78% then I not only disagree but I wonder where you got those numbers. I do not remember the bottom number, but am pretty sure the top length of H&A is 80%.

If you are saying that anything outside the correct length of lower girdle facets fails, then I absolutely agree NOT DISAGREE, They do fail to be H&A. This would be agreed on by the vendors of the H&A diamonds, the cutters of H&A diamonds, and the Japanese Laboratories and HRD who grade for the patterns of the H&A diamonds. That you have established that other patterns also have wonderful light performance and optical symmetry is wonderful and true, but it does NOT MAKE THEM H&A.

If you are saying that optical symmetry and top light performance can be garnered by other patterns than H&A, then I absolutely agree with you. I said the same thing in the other thread and you said I miss your point.

If your point is that you can call anything you want H&A, then I am not missing your point, just strongly disagreeing with it. There are and have been recognized standards since the Japanese Labs graded for H&A long before we started selling them in this country.

I continue to agree with Paul that we should not call them H&A but rather symmetry and contrast patterns, which would alleviate your problems with wanting to call your very long lower girdle facets with the clefted hearts H&A, which they are not. I furrther agree with John Pollard that we need to call them something other than symmetry patterns to avoid confusing the public, who are already confused by the difference in physical symmetry and optical symmetry without us adding a third kind of symmetry.

Wink

I often see 80% lgf quoted as max for true H&A''s. Has anyone seen a true H&A (closed hearts) with an 80 lgf? Every diamond I have seen with 80% lgf has clearly had clefts in the hearts. I was just wondering how you could accomplish closed hearts with 80% lgf.

 

[John P]

Date: 8/1/2008 8:41:24 PM
Author: agc
I often see 80% lgf quoted as max for true H&A's. Has anyone seen a true H&A (closed hearts) with an 80 lgf? Every diamond I have seen with 80% lgf has clearly had clefts in the hearts. I was just wondering how you could accomplish closed hearts with 80% lgf.

Hi AGC.

In near-Tolks in common sizes >79% will produce a small incision. This has been permitted in traditional patterning, as-documented in the PS tutorial and HRD's published criteria.

PS tutorial:

>

HRD's "common parameter" for lower halves is cited as 77%. They cite 74-79% as a practical range but I believe they are more liberal in actuality...at least from the graphic below they seem to agree with Brian Gavin's 80%.

From HRD's H&A Cut Parameters (acknowledgment to HRD):

Variation in the pavilion half length influences the gap between the v-shaped arrow head and the heart shape. Lowering the pavilion half length (79%) makes the gap between the V's and the hearts wider and creates incisions in the heart shapes. The arrows become thinner. It should be noticed that the range of acceptable half lengths is very narrow."

For reference, here are 80% lower halves, modeled in a modern Tolkowsky:

 

[agc]

Thanks John. Will the HRD system specify % cleft length needed to have low vs med vs high penalty such as 1-8% cleft= low penalty and 9-15% cleft = med penalty etc. ?

Regards
Andy