H&A performance

[glitterata]

Date: 10/13/2009 5:08:27 PM
Author: Wink
Some of us experts believe that the larger virtual facets formed by better optical symmetry will make the diamond perform better than one with more numberous and smaller virtual facets, particularly when many of the additional facets are below the limit of discerment by the unaided human eye.


Wink

Wink, I don''t see how that can be right, or else Old European Cut diamonds would "perform" better than modern brilliant ideal cuts with wonderful symmetry, since OECs have much bigger virtual facets.

In fact, I love my OEC for its big virtual facets, which give flashes of amazing fire. But it''s not as bright as the AGS ideal, fantastically symmetrical Infinity diamonds I bought from you.

Also, it''s possible to manipulate the size of the virtual facets without necessarily increasing the symmetry.

I love the pretty star pattern in my Infinities. I love knowing that they''re the result of an amazing level of craftsmanship. But my not-that-symmetrical OEC beats them hands down for large virtual facets.

 

[Paul-Antwerp]

Glitterata,

I think that you missed the nuance in Wink''s remark, and took it too literally. Then again, it is difficult to always give the full picture in the limited frame of a post here.

Actually, Wink is referring to the fact that with less optical symmetry, a diamond forms a number of extra virtual facets, most of them of an unnoticeable size. As such, this surface of the diamond contributes less to brightness, reduces the observability of fire, and reduces the intensity of the scintillation.

He is not refering to a comparison with a diamond with larger virtual facets, just to a comparison between optically symmetrical and non-symmetrical.

Live long,

 

[Karl_K]

Date: 10/27/2009 5:02:21 PM
Author: glitterata

Date: 10/13/2009 5:08:27 PM

Author: Wink

Some of us experts believe that the larger virtual facets formed by better optical symmetry will make the diamond perform better than one with more numberous and smaller virtual facets, particularly when many of the additional facets are below the limit of discerment by the unaided human eye.



Wink

Wink, I don''t see how that can be right, or else Old European Cut diamonds would ''perform'' better than modern brilliant ideal cuts with wonderful symmetry, since OECs have much bigger virtual facets.


In fact, I love my OEC for its big virtual facets, which give flashes of amazing fire. But it''s not as bright as the AGS ideal, fantastically symmetrical Infinity diamonds I bought from you.


Also, it''s possible to manipulate the size of the virtual facets without necessarily increasing the symmetry.


I love the pretty star pattern in my Infinities. I love knowing that they''re the result of an amazing level of craftsmanship. But my not-that-symmetrical OEC beats them hands down for large virtual facets.

I don''t agree with that statement 100% either.
It is not that easy.
No one has a 100% handle on virtual facets.
Out of the major groups AGS is closest and they will admit they dont have all the answers.
I manipulate virtual facets daily in designing diamonds and I will admit to not having all the answers.

The biggest and unavoidable fact is that there will never be a diamond cut with perfect virtual facets.
The viewers(h&a, ASET, IS) are all low resolution when it comes to showing individual virtual facets and blend them together.
Generated images can show a higher resolution but when you scan a diamond you lose a lot of it to scanner error and the limit becomes the resolution of the scanner and things the scanner can not measure.

 

[Paul-Antwerp]

Karl,

I tried to clarify Wink''s point and think that I did in a clear way.

Why do you make it confusing again by talking about something completely different?

Live long,

 

[Karl_K]

Date: 10/28/2009 11:25:32 AM
Author: Paul-Antwerp
Karl,


I tried to clarify Wink''s point and think that I did in a clear way.


Why do you make it confusing again by talking about something completely different?


Live long,

Hi Paul,
glitterata has shown a lot of interest in virtual facets and is interested in learning more about them.
So it was a good opportunity to continue to educate about them.

Second I didn''t read your post before answering.

 

[glitterata]

Thanks, Karl and Paul.

Paul, you're saying that when you compare two diamonds with similar proportions but one has high optical symmetry and the other doesn't, the one with lower symmetry will have some virtual facets that are too small to see and make it less bright/fiery/sparkly. Is that it?

But why isn't my objection also true? If larger virtual facets are better when comparing two stones with similar proportions, why aren't larger virtual facets also better when comparing two stones with dissimilar proportions? Why aren't OECs better than modern RBs, assuming both are cut to minimize leakage?

Is the answer just that it's a matter of personal taste whether you prefer smaller or larger virtual facets, once the virtual facets are large enough to see?

 

[Lord Summerisle]

Date: 10/27/2009 1:40:58 PM
Author: John Pollard

Date: 10/27/2009 12:14:59 PM


#4 Photography


#4 is easiest to address. Inexperienced or time-pressed photographers may not get the lens of the camera perfectly level with the plane of the platform on which the diamond is resting. Even a fraction of a degree will make a difference with the hundreds of reflections happening in such a tiny object. When slightly ''off'' the main patterns - which draw most light - can still resolve, but the minor facet reflections can appear off. This is why I preach (again and again) that 2D photos are nice but...just like clarity...and just like color...it is impossible to decisively evaluate 3D precision of a diamond without having it in hand. Anyone who has seen two diamonds in a H&A viewer, one with the highest level of precision and one that comes close, in a high quality H&A viewer knows the differences are far more evident in real life, with stereo vision & depth perception, than what is possible in 2D photography - and no ''cheating'' of photos can occur in real life.

I must say that was my first thought on reading the OP. that the pictures he''s seeing on the vendors websites on the hearts image are subject to a slight photographic distortion in that the diamonds has not been placed off the dead centre of the lens, and as such, shows a distortion in the hearts image. often can be seen by a slight curling of the arrow heads to a point not in the centre of the diamond.

same as if the camera is at a slight tilt to the diamond.

Of course theres the more diamond defect Sir John points out, but i do wonder if alot of it is down to the people taking the images not having sufficient time to set up each diamond under the camera to get the ''perfect'' hearts image.

in comparison to the Brian Gavin H&A thats in the Hearts and Arrows tutorial, - isnt that the very first ''hearts and arrows'' diamond that Brian''s father cut to Brian''s specs, and as such was a show case for the Alpha company (long before Whiteflash was set up) so alot of time would have been taken to get the shot ''just so'' something that just isnt economic to get set up each time, so getting as accurate as possible, in a short time so pictures can be uploaded withe diamond details.

It wasnt so long a go that Whiteflash didnt have the Hearts image on the diamond details page, but would take a picture if the customer wished, as they just didnt have the resources to spend the time taking the shots. Which they now have, so do take the ''hearts'' image as a matter of course.

 

[Paul-Antwerp]

Yes, indeed, Glitterata, in a diamond with the same proportions, optical asymmetry will create extra virtual facets, which will mostly be of such a small size that they do not contribute positively. This is what Wink is refering to.

Your objection is something totally different. Whether big, medium-size, small virtual facets are best, is undetermined and most probably a matter of taste. Too small however is not good, in the sense that it is surface not contributing positively, and in the sense that it takes away some surface of the larger virtual facets (and these can be big, medium-size or small).

In your case, you love your Infinity, because it has a pleasing mix of big, medium-size and small virtual facets, and this is maximized because there are hardly any ''extra virtual facets of very small size'' because of the stone''s optical symmetry. Someone else however might prefer an OEC, because of the big virtual facets.

Live long,

 

[Karl_K]

Date: 10/28/2009 12:36:58 PM
Author: glitterata
Thanks, Karl and Paul.


Paul, you''re saying that when you compare two diamonds with similar proportions but one has high symmetry and the other doesn''t, the one with low symmetry will have some virtual facets that are too small to see and make it less bright/fiery/sparkly. Is that it?


But why isn''t my objection also true? If larger virtual facets are better when comparing two stones with similar proportions, why aren''t larger virtual facets also better when comparing two stones with dissimilar proportions? Why aren''t OECs better than modern RBs, assuming both are cut to minimize leakage?


Is the answer just that it''s a matter of personal taste whether you prefer smaller or larger virtual facets, once the virtual facets are large enough to see?

What size virtual facets are most effective depends on the lighting.
A diamond with all one size of virtual facet will be great in some lighting but not so great in others.
Over simplified:
large virtual facets are more effective in lower and softer light than smaller virtual facets. The trade off is fewer events.
Small virtual facets are most effective in bright direct light and provide more events.
Med. virtual facets are in the middle.

If you know the lighting and the diamond will mostly be viewed in that lighting you can tune the virtual facet size for that lighting.
Since diamonds are viewed under many lighting conditions a mix of virtual facet sizes is best.
As indoor lighting has changed and is changing rapidly again the ideal mix of virtual facet sizes will and has changed.
This does not mean that the other mixes are bad and indeed some may prefer a different mix.

Since different designs act differently under tilt with regards to changes in virtual facet sizes the mix is different for step cuts and round brilliants for example.

 

[John P]

Date: 10/28/2009 12:36:58 PM
Author: glitterata
Thanks, Karl and Paul.

But why isn't my objection also true? If larger virtual facets are better when comparing two stones with similar proportions, why aren't larger virtual facets also better when comparing two stones with dissimilar proportions? Why aren't OECs better than modern RBs, assuming both are cut to minimize leakage?

Is the answer just that it's a matter of personal taste whether you prefer smaller or larger virtual facets, once the virtual facets are large enough to see?

Different configurations Glitterata.

Antique cuts were fashioned with very wide pavilion mains and short lower halves because the lighting of the day (gas lamp) was not as direct. Those wide mains served to catch and reflect the soft social lighting of that age (gas lanterns) and large mains + high crowns were conducive to fire. As an aside, high crowns were also practical prior to the rotary saw. Tables were grinded down in those days and often measured about 40%.

The modern brilliant is fashioned to dazzle with bright lighting of the kind in jewelry store showrooms. To accomplish this the pavilion mains are far more narrow and lower halves much longer. The result is more intensity. Under normal modern lighting the RB is (so far) the most effective configuration for light return.

If you configure the diamond to get larger virtual facets you lose intensity, particularly when shortening the lower halves (which makes a RB more like an antique cut). Eightstar was made famous by working toward larger VFs in a RB config - not that this was discussed in the 80s. They shortened the lower halves to the low 70% range and painted the upper halves so the angles were closer; in effect making a single-ish facet from each pair of neighboring uppers. This created larger VFs and met with rave reviews in soft lighting, but that configuration has been penalized in the brightness category in some recent metrics.

In very layman terms, think of yourself in a shower (I am not being fresh, I promise). The water is light return. If you adjust the nozzle so the water is cascading down in large, weighty sheets it's kind of like what wide pavilion mains and short lower halves do with the light. If you twist the nozzle so that the water narrows and washes you with more intensity it's more like narrow mains and long lower halves... In modern lighting diamond designers want the "POW" factor so modern RBs use the more intense config. However there is incredible charm in the old config...it's just not as "POW" in bright lights.

Date: 10/28/2009 12:36:58 PM
Author: glitterata
Thanks, Karl and Paul.

Paul, you're saying that when you compare two diamonds with similar proportions but one has high symmetry and the other doesn't, the one with low symmetry will have some virtual facets that are too small to see and make it less bright/fiery/sparkly. Is that it?

It's more relevant in modern brilliants, since the VFs are smaller to begin with per the explanation above. Taking this farther, small VFs are also why some peope find diamonds with extra facets too busy or scintillation too "needlelike" (describing performance).

 

[glitterata]

Thank you for those illuminating posts, Paul & Karl. In fact, I sometimes prefer my OEC and sometimes my Infinity, and it depends a lot on the lighting, as Karl described.

How does optical symmetry affect the look of the diamond once it''s tilted? Will the more symmetrical diamond still have fewer invisibly-small virtual facets?

 

[John P]

Date: 10/28/2009 12:52:32 PM
Author: Lord Summerisle

I must say that was my first thought on reading the OP. that the pictures he's seeing on the vendors websites on the hearts image are subject to a slight photographic distortion in that the diamonds has not been placed off the dead centre of the lens, and as such, shows a distortion in the hearts image. often can be seen by a slight curling of the arrow heads to a point not in the centre of the diamond.

same as if the camera is at a slight tilt to the diamond.

Of course theres the more diamond defect Sir John points out, but i do wonder if alot of it is down to the people taking the images not having sufficient time to set up each diamond under the camera to get the 'perfect' hearts image.

in comparison to the Brian Gavin H&A thats in the Hearts and Arrows tutorial, - isnt that the very first 'hearts and arrows' diamond that Brian's father cut to Brian's specs, and as such was a show case for the Alpha company (long before Whiteflash was set up) so alot of time would have been taken to get the shot 'just so' something that just isnt economic to get set up each time, so getting as accurate as possible, in a short time so pictures can be uploaded withe diamond details.

It wasnt so long a go that Whiteflash didnt have the Hearts image on the diamond details page, but would take a picture if the customer wished, as they just didnt have the resources to spend the time taking the shots. Which they now have, so do take the 'hearts' image as a matter of course.

Thanks for back-on-topic M'Lord.

And that's an important point. Certainly, a company will give a "signature image" the care and attention a magazine gives the cover photo. Whereas H&A photos taken in sequence for a brand - even though all the diamonds may be "model" worthy - must be treated more like photos of everyone in this year's class for the yearbook.

 

[glitterata]

I apologize for the threadjack. I do tend to wander off topic!

 

[John P]

Date: 10/28/2009 2:03:31 PM
Author: glitterata

I apologize for the threadjack. I do tend to wander off topic!

I only recognize it because I''m a perp myself Glitterata.

 

[Serg]

Date: 10/28/2009 12:56:41 PM
Author: Paul-Antwerp
Yes, indeed, Glitterata, in a diamond with the same proportions, optical asymmetry will create extra virtual facets, which will mostly be of such a small size that they do not contribute positively. This is what Wink is refering to.


Your objection is something totally different. Whether big, medium-size, small virtual facets are best, is undetermined and most probably a matter of taste. Too small however is not good, in the sense that it is surface not contributing positively, and in the sense that it takes away some surface of the larger virtual facets (and these can be big, medium-size or small).


In your case, you love your Infinity, because it has a pleasing mix of big, medium-size and small virtual facets, and this is maximized because there are hardly any 'extra virtual facets of very small size' because of the stone's optical symmetry. Someone else however might prefer an OEC, because of the big virtual facets.


Live long,

re:Yes, indeed, Glitterata, in a diamond with the same proportions, optical asymmetry will create extra virtual facets, which will mostly be of such a small size that they do not contribute positively.

It is quite misleading statement because:
1) asymmetry creates big range of extra virtual facets. Some of them are small but give positive input
2) it is not correct to compare Number helpful and helpless extra virtual facets. there is important to compare area such facets and additional ETAS what such facets add ( number and probability additional flashes .)
3) Even small extra facet can create big and bright flashes. See for example princess cut
Moreover if two diamonds have similar average proportions and diamond with low symmetry has less brightness it is not proof what asymmetry is main reason of low brightness. There are other more important reasons than asymmetry if we speak about brightness . Flatness of facet is critical for brightness too.

 

[Paul-Antwerp]

Thank you, Sergey, for confirming what I have said.

Too bad that you brought it in such a confusing way, that it seems as if we are contradicting.

Live long,

 

[Regular Guy]

Sorry but...just thought I''d offer a quick hello...

Date: 10/28/2009 12:52:32 PM
Author: Lord Summerisle

to Lord S!

 

[Garry H (Cut Nut)]

Date: 10/28/2009 3:19:09 PM
Author: Serg

Date: 10/28/2009 12:56:41 PM

Author: Paul-Antwerp

Yes, indeed, Glitterata, in a diamond with the same proportions, optical asymmetry will create extra virtual facets, which will mostly be of such a small size that they do not contribute positively. This is what Wink is refering to.



Your objection is something totally different. Whether big, medium-size, small virtual facets are best, is undetermined and most probably a matter of taste. Too small however is not good, in the sense that it is surface not contributing positively, and in the sense that it takes away some surface of the larger virtual facets (and these can be big, medium-size or small).



In your case, you love your Infinity, because it has a pleasing mix of big, medium-size and small virtual facets, and this is maximized because there are hardly any 'extra virtual facets of very small size' because of the stone's optical symmetry. Someone else however might prefer an OEC, because of the big virtual facets.



Live long,

re:Yes, indeed, Glitterata, in a diamond with the same proportions, optical asymmetry will create extra virtual facets, which will mostly be of such a small size that they do not contribute positively.


It is quite misleading statement because:

1) asymmetry creates big range of extra virtual facets. Some of them are small but give positive input

2) it is not correct to compare Number helpful and helpless extra virtual facets. there is important to compare area such facets and additional ETAS what such facets add ( number and probability additional flashes .)

3) Even small extra facet can create big and bright flashes. See for example princess cut

Moreover if two diamonds have similar average proportions and diamond with low symmetry has less brightness it is not proof what asymmetry is main reason of low brightness. There are other more important reasons than asymmetry if we speak about brightness . Flatness of facet is critical for brightness too.

I think I just failed to upload an image
Edited later - yes i did fail - moved to firefox and not liking it.

 

[Lord Summerisle]

Date: 10/29/2009 12:09:51 AM
Author: Regular Guy
Sorry but...just thought I''d offer a quick hello...

Date: 10/28/2009 12:52:32 PM

Author: Lord Summerisle

to Lord S!

Forever lurking... and learning.

 

[risingsun]

I think that the tutorials on HPD about the relationship between performance [optical symmetry] and precision in the H&A diamond are extremely helpful.
http://highperformancediamonds.com/index.php?page=education-performance

Combine this information with the data on virtual facets and you will have a sound knowledge base from which to choose a wonderful H&A stone.
This assumes that you have read the basics on basic diamond knowledge including cut, reflector technology, H&A viewer, the 4 "c's" and have observed a variety of diamonds IRL. If I have forgotten anything, chalk it up to fibro fog

 

[DavR]

I would also recommend checking out the H&A grading manual that was posted earlier so you can tell exactly where your H&A image falls (taking picture distortion into account).

 

[Serg]

Date: 10/29/2009 12:01:02 PM
Author: risingsun
I think that the tutorials on HPD about the relationship between performance [optical symmetry] and precision in the H&A diamond are extremely helpful.

http://highperformancediamonds.com/index.php?page=education-performance


Combine this information with the data on virtual facets and you will have a sound knowledge base from which to choose a wonderful H&A stone.

This assumes that you have read the basics on basic diamond knowledge including cut, reflector technology, H&A viewer, the 4 ''c''s'' and have observed a variety of diamonds IRL. If I have forgotten anything, chalk it up to fibro fog

Risingsun,

re:I think that the tutorials on HPD about the relationship between performance [optical symmetry] and precision in the H&A diamond are extremely helpful.

1) Performance is NOT Optical symmetry
2) Moreover I find nothing in this tutorial about relationship between optical symmetry and precision. Please give exact place in this or any other document when I can find something about relationship between performance and optical symmetry or between performance and cut precision or between performance and precision. I will very happy ready something helpful

 

[Serg]

If Diamond “B” has better symmetry than Diamond “A”, it does not mean what diamond “B” has more red in ASET/IS than diamond “A”

If diamond “C” has more red in ASET/IS than diamond “B”, it does not mean what diamond “C” is more Bright than diamond “B”
If Diamond “D” is more bright than Diamond “C”, it does not mean what diamond “D” has better brilliancy than diamond “C”
If Diamond “E” has more Brilliancy than Diamond “D”, it does not mean what diamond “E” has better Performance than diamond “D”


It is right even if all these diamonds have zero absorption and Excellent polish and Facet Flatness ( in over words if we speak about CUT performance).
If we speak about Diamond Performance the correlation between Symmetry and Performance even less.

 

[risingsun]

Of course, optical symmetry has to do with precision in cutting the diamond. My mistake, Serg. In reading the HPD tutorials, excerpt highlighted below, I have gotten the impression that in a stone, which already has excellent performance characteristics, the precision of cut can improve upon the overall appearance of the diamond. I am also basing my remarks upon comments made and recorded by Peter Yantzer on the same topic. His comments may be found on the HPD website.

Next Up: Cut Precision
You’ve learned how to measure overall light return, brightness and contrast. Now read our Precision Tutorial to see how optical symmetry (aka “Hearts & Arrows” in rounds) can take contrast, dispersion and scintillation to a higher level in diamonds that already have top performance.

Benefits of Cut Precision
Cut Precision fine-tunes diamonds which already enjoy top performance. The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones). Precision cutting maximizes the return of all available light, even in softer lighting conditions. This is a logical result of all of the facets, the tiny mirrors inside the diamond, brought into precise alignment with each other. Face up color is also improved when light gets in and out of a diamond with more intensity. This can be noted in many diamonds with above-average performance. High performance coupled with top cut precision enhances the effect even more.



Wink, Paul or John would be of more help, as one or more of them wrote the tutorial. Wink should be able to provide you with the video/comments made by Peter.

ETA: I don't own an Infinity diamond, but I do have another branded H&A stone. I openly place my [potential] bias on the table

 

[Serg]

Date: 10/29/2009 3:59:42 PM
Author: risingsun
Of course, optical symmetry has to do with precision in cutting the diamond. My mistake, Serg. In reading the HPD tutorials, excerpt highlighted below, I have gotten the impression that in a stone, which already has excellent performance characteristics, the precision of cut can improve upon the overall appearance of the diamond. I am also basing my remarks upon comments made and recorded by Peter Yantzer on the same topic. His comments may be found on the HPD website.


Next Up: Cut Precision

You’ve learned how to measure overall light return, brightness and contrast. Now read our Precision Tutorial to see how optical symmetry (aka “Hearts & Arrows” in rounds) can take contrast, dispersion and scintillation to a higher level in diamonds that already have top performance.


Benefits of Cut Precision

Cut Precision fine-tunes diamonds which already enjoy top performance. The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones). Precision cutting maximizes the return of all available light, even in softer lighting conditions. This is a logical result of all of the facets, the tiny mirrors inside the diamond, brought into precise alignment with each other. Face up color is also improved when light gets in and out of a diamond with more intensity. This can be noted in many diamonds with above-average performance. High performance coupled with top cut precision enhances the effect even more.





Wink, Paul or John would be of more help, as one or more of them wrote the tutorial. Wink should be able to provide you with the video/comments made by Peter.


ETA: I don''t own an Infinity diamond, but I do have another branded H&A stone. I openly place my [potential] bias on the table

Resigsun,
re:

Cut Precision fine-tunes diamonds which already enjoy top performance. The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones). Precision cutting maximizes the return of all available light, even in softer lighting conditions. This is a logical result of all of the facets, the tiny mirrors inside the diamond, brought into precise alignment with each other.

--

It is not Proof, it is not knowledge, it is not explanation . It could be Hypothesis , It could be Dream, It could be propaganda.

I will try explain why I think so. Lets try easiest explanation ( there are other technical explanations )

1) You can see ''''better-defined contrast pattern ", smallest number VFs, high level symmetry pattern ONLY when optical axis of Viewer ( as H&A, ASET, IS) is perpendicular to diamond table and close to diamond center
2) try tilt diamond on 5-7 degree OR/AND shift diamonds on several mm, and you CAN NOT see more ''''better-defined contrast pattern ", you can not recognize "True H&A" from " commercial H&A ".
3) if you have two eyes , optical axes of both your eyes can not be perpendicular to diamond table in same time. You have not any chance to see smallest number VFs as you can see in H&A Viewer. All times you will see many additional small VFs( of course even for tilt position round diamond with highest level symmetry could have less number than diamond with less then highest level symmetry. But did Infinity or WF or AGS did such comparison ? do they know how number of VFS facets depends from tilt AND symmetry level ?)

ABout Peter Y. statement. I know quite opposite him statement about H&A diamonds. I hope somebody will publish it here.

 

[Paul-Antwerp]

Very good explanation, Sergey, if the eyes were the source of light. However, they happen to be at the other end of the equation.

 

[Garry H (Cut Nut)]

Date: 10/29/2009 3:59:42 PM
Author: risingsun
Of course, optical symmetry has to do with precision in cutting the diamond. My mistake, Serg. In reading the HPD tutorials, excerpt highlighted below, I have gotten the impression that in a stone, which already has excellent performance characteristics, the precision of cut can improve upon the overall appearance of the diamond. I am also basing my remarks upon comments made and recorded by Peter Yantzer on the same topic. His comments may be found on the HPD website.


Next Up: Cut Precision

You’ve learned how to measure overall light return, brightness and contrast. Now read our Precision Tutorial to see how optical symmetry (aka “Hearts & Arrows” in rounds) can take contrast, dispersion and scintillation to a higher level in diamonds that already have top performance.


Benefits of Cut Precision

Cut Precision fine-tunes diamonds which already enjoy top performance. The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones). Precision cutting maximizes the return of all available light, even in softer lighting conditions. This is a logical result of all of the facets, the tiny mirrors inside the diamond, brought into precise alignment with each other. Face up color is also improved when light gets in and out of a diamond with more intensity. This can be noted in many diamonds with above-average performance. High performance coupled with top cut precision enhances the effect even more.





Wink, Paul or John would be of more help, as one or more of them wrote the tutorial. Wink should be able to provide you with the video/comments made by Peter.


ETA: I don''t own an Infinity diamond, but I do have another branded H&A stone. I openly place my [potential] bias on the table

The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones).

I believe this comment from Peter is NQR.
To the best of my knowledge dispersion other than pure spectral colors is impossible in singly refractive gemstones.
In this calcite from the Smithsonian you can see how doubly refractive gems can produce second order colors. Can anyone show me an example in diamond like this?

 

[Garry H (Cut Nut)]

Date: 10/29/2009 4:57:15 PM
Author: Serg

Date: 10/29/2009 3:59:42 PM

Author: risingsun

Of course, optical symmetry has to do with precision in cutting the diamond. My mistake, Serg. In reading the HPD tutorials, excerpt highlighted below, I have gotten the impression that in a stone, which already has excellent performance characteristics, the precision of cut can improve upon the overall appearance of the diamond. I am also basing my remarks upon comments made and recorded by Peter Yantzer on the same topic. His comments may be found on the HPD website.



Next Up: Cut Precision


You’ve learned how to measure overall light return, brightness and contrast. Now read our Precision Tutorial to see how optical symmetry (aka “Hearts & Arrows” in rounds) can take contrast, dispersion and scintillation to a higher level in diamonds that already have top performance.



Benefits of Cut Precision


Cut Precision fine-tunes diamonds which already enjoy top performance. The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones). Precision cutting maximizes the return of all available light, even in softer lighting conditions. This is a logical result of all of the facets, the tiny mirrors inside the diamond, brought into precise alignment with each other. Face up color is also improved when light gets in and out of a diamond with more intensity. This can be noted in many diamonds with above-average performance. High performance coupled with top cut precision enhances the effect even more.







Wink, Paul or John would be of more help, as one or more of them wrote the tutorial. Wink should be able to provide you with the video/comments made by Peter.



ETA: I don''t own an Infinity diamond, but I do have another branded H&A stone. I openly place my [potential] bias on the table

Resigsun,

re:


Cut Precision fine-tunes diamonds which already enjoy top performance. The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones). Precision cutting maximizes the return of all available light, even in softer lighting conditions. This is a logical result of all of the facets, the tiny mirrors inside the diamond, brought into precise alignment with each other.


--


It is not Proof, it is not knowledge, it is not explanation . It could be Hypothesis , It could be Dream, It could be propaganda.


I will try explain why I think so. Lets try easiest explanation ( there are other technical explanations )


1) You can see ''''better-defined contrast pattern '', smallest number VFs, high level symmetry pattern ONLY when optical axis of Viewer ( as H&A, ASET, IS) is perpendicular to diamond table and close to diamond center

2) try tilt diamond on 5-7 degree OR/AND shift diamonds on several mm, and you CAN NOT see more ''''better-defined contrast pattern '', you can not recognize ''True H&A'' from '' commercial H&A ''.

3) if you have two eyes , optical axes of both your eyes can not be perpendicular to diamond table in same time. You have not any chance to see smallest number VFs as you can see in H&A Viewer. All times you will see many additional small VFs( of course even for tilt position round diamond with highest level symmetry could have less number than diamond with less then highest level symmetry. But did Infinity or WF or AGS did such comparison ? do they know how number of VFS facets depends from tilt AND symmetry level ?)


ABout Peter Y. statement. I know quite opposite him statement about H&A diamonds. I hope somebody will publish it here.

ABout Peter Y. statement. I know quite opposite him statement about H&A diamonds. I hope somebody will publish it here.

Peter has told me before that AGSL does not consider H&A''s level symmetry has been proven to be superior in terms of human ability to notice a benefit.


Here is an attachment I tried to place yesterday. On the left is a very very bad sym stone and on the right a stone with the same average proportions in Ideal-scope and DETAS (which shows were you would see as a stone was rocked through 2 degrees away from the top down position).

Paul this can be done for each eye and if there is a light in any of those positions then each eye that has a flash in that place will see a sparkle in the diamond. I hope that clarify''s your question to Sergey.
For the record there is about a 2% better performance in ligth return, dark zones and contrast in the symmetrical stone on the right hand side of the image.

 

[Serg]

Date: 10/29/2009 6:22:05 PM
Author: Paul-Antwerp
Very good explanation, Sergey, if the eyes were the source of light. However, they happen to be at the other end of the equation.

Mr. Paul Slegers,

I advice you improve your background in cut optics and in optics . in connection with your comments seems You need learn a lot before to start discussion with me.
Until you improve your background and attitude I do not see any real possibility for me to teach you and change your mind
Be happy

 

[John P]

Date: 10/29/2009 6:30:43 PM
Author: Garry H (Cut Nut)


The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones).

I believe this comment from Peter is NQR.

Actually Garry, I believe this is originally from Marty Haske''s research. Peter may have mentioned it as well (?)