41 degree pavillion angle

[pyramid]

Thanks Michaelgem

Those articles are interesting, the contrast brilliance description of snappy that is exactly what I was meaning when I wrote about silver sparkles going on and off in the daimond.

I will not be disappointed in the fire, I like the fire too, I just like lots of brilliance more. Interesting in the other article where you describe the brown colour in the table as being reflections from beneath the diamond rather than leakage. I have read that light comes in the back of the stone as well as from the top so this would be where leakage is not a bad thing then.

 

[michaelgem]

Date: 7/17/2007 6:02:29 PM
Author: Pyramid
Thanks Michaelgem

Those articles are interesting, the contrast brilliance description of snappy that is exactly what I was meaning when I wrote about silver sparkles going on and off in the daimond.

I will not be disappointed in the fire, I like the fire too, I just like lots of brilliance more. Interesting in the other article where you describe the brown colour in the table as being reflections from beneath the diamond rather than leakage. I have read that light comes in the back of the stone as well as from the top so this would be where leakage is not a bad thing then.

You''re welcome, Pyramid,

I am glad that you read and enjoyed those articles. Not too many take the time to read what I am saying before questioning it. Understanding requires more than sound bites, but when you go into necessary detail you loose a lot of people. I usually err on the side of detail, and only keep the interest of motivated and avid diamond enthusiasts like yourself.

The contrast brilliance description of snappy for the look of the Ideal cut came from diamond advertising around the turn of the 20th century. It is mentioned in Al Gilbertson''s new book, "The American Cut, the first 100 years".

Eric Bruton, one of your countrymen, who wrote the definitive book on "Diamonds" from the early 70''s is the one who called the look "hard or sharp". It is not enough to design a bright diamond cut, it must possess the snappy, sharp look of contrast brilliance in typical illumination to be Ideal and possess ideal sparkle or scintellation.

Sometime, on another thread, I''d like to address light leakage along with retro-reflection and multiple internal reflections, all the factors contributing to poor performing areas in a diamond. What is perceived to be darker areas of extintion or color entrapment are often combinations of these performance negatives.

My comment that light leakage should better be called reflections from beneath the diamond was intended to get people thinking. After all, you are not seeing light that "leaked" away in those areas like the ring of death. You are actually seeing right through the diamond to the relative darkness that usually exists below. The Ideal cut is designed to reflect light from above where it usually exists, which is why any significant amount of leakage or reflections from the dark area below the diamond is not a good thing. (It may sound like Star Wars, but you don''t want a diamond to reflect light from the "dark side"

)

When the diamond is sufficiently tilted some reflections from below are unavoidable even in Ideal Cuts.

One of the properties of your Ideal cut is its ability to maintain brilliance, fire and sparkle under a greater amount of tilt than a lesser quality cut. AGS factors that quality trait into their grading system. It is also one of the reasons why a diamond with table size noticably greater than 60% is not an Ideal cut. As the table gets larger than that the girdle reflection, (another ring of death called a fish-eye) becomes apparent just inside the table edge with less tilt.

Ideal regards,

Michael

 

[pyramid]

Thanks for your knowledge Michaelgem.

 

[adamasgem]

Date: 7/15/2007 12:11:42 PM
Author: strmrdr
Here they are side by side.
The only difference I''m seeing is the jaggedness of the center and the slightly larger reflection between the arrows which I expected but the jaggedness I didn''t.

Storm.. Any jaggedness you see may be the combined effect of an ASSYMETRIC lighting model with a particular stone

 

[adamasgem]

Date: 7/15/2007 12:18:26 PM
Author: michaelgem

Date: 7/15/2007 12:11:42 PM
Author: strmrdr
Here they are side by side.
The only difference I''m seeing is the jaggedness of the center and the slightly larger reflection between the arrows which I expected but the jaggedness I didn''t.

Not to worry, Strmrdr,

A slight reduction in lower half length is all that is needed to correct the ''jaggedness''. A side benefit will be wider mains = larger flashes of brilliance and fire.

Michael

Cowing: A symmetric stone in a symmetric lighting environment will render a SYMMETRIC image. You are trying to blow too much smoke and you are failing technically..

 

[adamasgem]

1) "People" talk about sweet spot, and equate geometric center for some grading paradigm, with optimal performance, which is flat wrong, and should be STOPPED

2) Any optimal performance "spot" is a function of the lighting envirornment used, if X number of evaluators use X different environments they will come up with X different "optimal" positions (or or facet combinations)

3) The optimal position of any performance metric is technically a function of the inherent absorption characteristics of the stone AND the SIZE of the stone, it is a very NON LINEAR process.

4) Within a very small BOX (as in a GIA or AGS paradigm) there are localized maxima and minima, it is not necessarily a smooth function, and we have shown that before.

 

[Regular Guy]

Date: 7/22/2007 3:02:34 PM
Author: adamasgem

2) Any optimal performance ''spot'' is a function of the lighting envirornment used, if X number of evaluators use X different environments they will come up with X different ''optimal'' positions (or or facet combinations)

Marty,

Not sure what, for example, the AGS metric is on this...but...rather than

a) looking for all the theoretical lighting environments, or
b) asking a shopper to go for as many as they can...you know
1) between their legs
2) over the shoulder
3) on top of Mout Meru...
c)...one would think an expert position could be assumed, in consideration of a broad brush set of assumptions about
1) a typical set of real world lighting environments many people will encounter
2) an enumerated set of these, if necessary, in order to explicate them
d) since there is no real reasonable expectation anyone shopping could try so many of these out, and
e) some rational basis could be expected to be accounted for in developing an expert opinion for ginning up a set of lighting environments to be accounted for

does AGS already define this?

And if they do not...is this a problem? From the point of view of ray tracing, their approach seems to be pretty respected.

Regards,

 

[strmrdr]

Date: 7/22/2007 3:52:57 PM
Author: Regular Guy

does AGS already define this?

And if they do not...is this a problem? From the point of view of ray tracing, their approach seems to be pretty respected.

Regards,

Hey RG you know the answer to this if you think about it.
ASET 30 and ASET 40 is the base.

 

[adamasgem]

Date: 7/22/2007 3:52:57 PM
Author: Regular Guy

Date: 7/22/2007 3:02:34 PM
Author: adamasgem

2) Any optimal performance ''spot'' is a function of the lighting envirornment used, if X number of evaluators use X different environments they will come up with X different ''optimal'' positions (or or facet combinations)

Marty,

Not sure what, for example, the AGS metric is on this...but...rather than

a) looking for all the theoretical lighting environments, or
b) asking a shopper to go for as many as they can...you know
1) between their legs
2) over the shoulder
3) on top of Mout Meru...
c)...one would think an expert position could be assumed, in consideration of a broad brush set of assumptions about
1) a typical set of real world lighting environments many people will encounter
2) an enumerated set of these, if necessary, in order to explicate them
d) since there is no real reasonable expectation anyone shopping could try so many of these out, and
e) some rational basis could be expected to be accounted for in developing an expert opinion for ginning up a set of lighting environments to be accounted for

does AGS already define this?

And if they do not...is this a problem? From the point of view of ray tracing, their approach seems to be pretty respected.

Regards,

I would agree that the AGS position is well respected, much more so than GIA''s since they (AGS) use the actual stones'' scan showing assymetry aspects of the stone, and not the averaged, half assed rounded and symmetrical measurements of GIA, and I would expect that it (the AGS analysis) will also improve and evolve, in part because of computing power and the ability to process more data.

 

[adamasgem]

Date: 7/22/2007 3:02:34 PM
Author: adamasgem
1) ''People'' talk about sweet spot, and equate geometric center for some grading paradigm, with optimal performance, which is flat wrong, and should be STOPPED

2) Any optimal performance ''spot'' is a function of the lighting envirornment used, if X number of evaluators use X different environments they will come up with X different ''optimal'' positions (or or facet combinations)

3) The optimal position of any performance metric is technically a function of the inherent absorption characteristics of the stone AND the SIZE of the stone, it is a very NON LINEAR process.

4) Within a very small BOX (as in a GIA or AGS paradigm) there are localized maxima and minima, it is not necessarily a smooth function, and we have shown that before.

I''ll add that lighting INCLUDES the spectrum of the light, what might be optimal for NYC noon "daylight" might not be as optimal for Miami "noon" daylight, all other factors being equal.

Which goes to the point of someone here crowing about Henry Morse and 34/41.

SYMMETRIC Gas light vs SYMMETRIC incandescent vs SYMMETRIC flourescent vs some color temperature of "SYMMETRIC" daylight will ALL give differing relative "goodness" results, and "look" to the diamond, subtle or maybe not subtle, on either an absorbing or non aborbing "ideal" stone. Basic laws of physics.

Throw in assymetry in the lighting model or the stone and you can get radical changes, as shown long ago by tilting the stone.

You can design a stone to maximize anyones given metric for ANY SPECIFIC environment, especially when you throw in point sources where the aspect angle of the source relative to the stone can make serious changes in the perceived metric results.

 

[adamasgem]

To illustrate the complexity of the problem some people try to simplify by talking about a given set of numbers like 34/41, or some "authorities" have tried to whitewash and dumb down by averaging and then rounding, here is the SAME stone photographed in a "relatively" symmetric environment of over 10000 "point" sources of white light, all the same size, so as to as well as physically possible, not alias the results.

Camera conditions and position fixed.

Fiducial marks are inked on the stone tray for reference, stone has rotated in the fixed environment.

Which "stone" is lighter, "brighter", better ????

Now this happens to be a VERY VERY symmetric stone, by the way, BUT it IS NOT perfectly SYMMETRIC.

People who use DiamondCalc can get a simplistic idea of this effect by using the "disco" light model (5 or 6 point sources if I remember, and rotate any symmetric or assmetric stone model stone about the table/culet axis.

I have better things to do than listen to a 34/41 rant from self promoters..

 

[pyramid]

Storm

I just wanted to say that the link for this stone I have shows the jagged appearance in the first photo and other photo but in the idealscope it is not there. Edited I may be able to see it in the idealscope I think now. Adamsgem said about it may be assymetric lighting or stone. I think I am posting what you are talking about anyway.


http://www.goodoldgold.com/diamond/3314

 

[strmrdr]

Date: 7/22/2007 8:17:55 PM
Author: Pyramid
Storm

I just wanted to say that the link for this stone I have shows the jagged appearance in the first photo and other photo but in the idealscope it is not there. Edited I may be able to see it in the idealscope I think now. Adamsgem said about it may be assymetric lighting or stone. I think I am posting what you are talking about anyway.


http://www.goodoldgold.com/diamond/3314

Im not sure why such a big deal is being made of it.
I just was commenting that it was unexpected not that it means anything,,,,,

 

[JohnQuixote]

Date: 7/22/2007 5:34:50 PM
Author: adamasgem

Camera conditions and position fixed.

Fiducial marks are inked on the stone tray for reference, stone has rotated in the fixed environment.

Every time I see one of your 10,000 point source photos I'm blown away. It may be proprietary but what camera settings do you use to capture such color at those lighting levels? No problem if it's private. I especially like that you've managed to escape the 'dark arrow' obstruction we must put up with in typical face-up diamond photos (a function of your lighting environment design I'm sure).

 

[Lynn B]

Date: 7/23/2007 9:58:53 AM
Author: JohnQuixote

Every time I see one of your 10,000 point source photos I''m blown away. It may be proprietary but what camera settings do you use to capture such color at those lighting levels? No problem if it''s private. I especially like that you''ve managed to escape the ''dark arrow'' obstruction we must put up with in typical face-up diamond photos (a function of your lighting environment design I''m sure).

You and me both, John!

Breathtaking photos, for sure. YOW-SA!!!

 

[WinkHPD]

Date: 7/23/2007 6:31:19 PM
Author: Lynn B

Date: 7/23/2007 9:58:53 AM
Author: JohnQuixote

Every time I see one of your 10,000 point source photos I''m blown away. It may be proprietary but what camera settings do you use to capture such color at those lighting levels? No problem if it''s private. I especially like that you''ve managed to escape the ''dark arrow'' obstruction we must put up with in typical face-up diamond photos (a function of your lighting environment design I''m sure).

You and me both, John!

Breathtaking photos, for sure. YOW-SA!!!

Okay, I love the photos, but what exactly am I looking at and how do I interpret them.

Wink wants to know more department.

 

[adamasgem]

Date: 7/22/2007 9:08:35 PM
Author: strmrdr

Date: 7/22/2007 8:17:55 PM
Author: Pyramid
Storm

I just wanted to say that the link for this stone I have shows the jagged appearance in the first photo and other photo but in the idealscope it is not there. Edited I may be able to see it in the idealscope I think now. Adamsgem said about it may be assymetric lighting or stone. I think I am posting what you are talking about anyway.


http://www.goodoldgold.com/diamond/3314

Im not sure why such a big deal is being made of it.
I just was commenting that it was unexpected not that it means anything,,,,,

My comment was meant to convey that it appeared that assymetric lighting was used, and that THAT can be the cause of the odd quazi symmetric rendering, independent of the cutting parameters (i.e. LGF) as was suggested, I believe incorrectly, by others.

 

[strmrdr]

Date: 7/23/2007 6:48:15 PM
Author: adamasgem
My comment was meant to convey that it appeared that assymetric lighting was used, and that THAT can be the cause of the odd quazi symmetric rendering, independent of the cutting parameters (i.e. LGF) as was suggested, I believe incorrectly, by others.

makes sense, thanks

 

[adamasgem]

Date: 7/23/2007 6:40:01 PM
Author: Wink

Date: 7/23/2007 6:31:19 PM
Author: Lynn B

Date: 7/23/2007 9:58:53 AM
Author: JohnQuixote

Every time I see one of your 10,000 point source photos I''m blown away. It may be proprietary but what camera settings do you use to capture such color at those lighting levels? No problem if it''s private. I especially like that you''ve managed to escape the ''dark arrow'' obstruction we must put up with in typical face-up diamond photos (a function of your lighting environment design I''m sure).

You and me both, John!

Breathtaking photos, for sure. YOW-SA!!!

Okay, I love the photos, but what exactly am I looking at and how do I interpret them.

Wink wants to know more department.

The photos were meant to convey, in this instance, that the patterning one sees, (light dark/areas as well as color) appears to not only be a function of the general cutting of a stone (as seen when you compare a well cut stone such as this versus your typical cutting with typical assymetry) BUT, even in what one would consider a non aliasing "uniform" environment (10000 points of light uniformly illuminating a stone) the same physical area of the stone may appear radically different because of the virtual facets. Use the line as a reference point.

This effect also easily shown by rotating a stone in Sergeys DiamondCalc "disco" lighting, which has a very limited set (6 I believe) point sources.

The effect would be less dramatic where the f stop, corresponding to your iris, is larger, as you would get more color blending both in the eye. and qualitativly more light/dark smudging, for lack of a better word.

Interpretation can take many forms, once you look at an excellent cut stone, then you can easily see the difference in a poorly cut stone, under the same conditions, and the correlation with cutting quality is somewhat remarkable, and might be similar in interpretation to, let''s say, an ASET image qualitatively.

 

[michaelgem]

The noise has returned to Pricescope

All the deconstructive comments noise has made at the conclusion of this thread have already been addressed and answered with clear, constructive discussion, analogies and demonstrations. No need for further elaboration.

Any who care can reread what several have already eloquently stated and backed up with clear, constructive demonstrations.

Statements from those individuals like Sergey Sivovolenko, that are always backed by constructive logic and demonstrations, are the ones that attention should be paid to.

Unfortunately, this fast moving Internet medium of information exchange makes it difficult for the typical reader to detect and receive Serg’s and others signals in the noise.

Michael

 

[WinkHPD]

Date: 7/23/2007 7:24:33 PM
Author: adamasgem

The photos were meant to convey, in this instance, that the patterning one sees, (light dark/areas as well as color) appears to not only be a function of the general cutting of a stone (as seen when you compare a well cut stone such as this versus your typical cutting with typical assymetry) BUT, even in what one would consider a non aliasing ''uniform'' environment (10000 points of light uniformly illuminating a stone) the same physical area of the stone may appear radically different because of the virtual facets. Use the line as a reference point.

This effect also easily shown by rotating a stone in Sergeys DiamondCalc ''disco'' lighting, which has a very limited set (6 I believe) point sources.

The effect would be less dramatic where the f stop, corresponding to your iris, is larger, as you would get more color blending both in the eye. and qualitativly more light/dark smudging, for lack of a better word.

Interpretation can take many forms, once you look at an excellent cut stone, then you can easily see the difference in a poorly cut stone, under the same conditions, and the correlation with cutting quality is somewhat remarkable, and might be similar in interpretation to, let''s say, an ASET image qualitatively.

Thank you for our conversation last evening. I particularly enjoyed understanding more about your beautiful phots and especially when you clued me in that all three stones were the same stone, just rotated slightly. I am amazed at how different the colors can be from the same part of the stone just by rotating slightly, especially when they are in reference to 10,000 different points of light. With that many points I would have incorrectly assumed that the stone would look similar from one angle to the next.

Could you do us the honor of perhaps starting a separate thread that would show us both well cut, like the EightStar used here and a less well cut and perhaps even a poorly cut stone, so that we can experience more of the differences that cutting makes?

Wink

 

[adamasgem]

Date: 7/24/2007 11:55:20 AM
Author: michaelgem

The noise has returned to Pricescope

All the deconstructive comments noise has made at the conclusion of this thread have already been addressed and answered with clear, constructive discussion, analogies and demonstrations. No need for further elaboration.

Any who care can reread what several have already eloquently stated and backed up with clear, constructive demonstrations.

Statements from those individuals like Sergey Sivovolenko, that are always backed by constructive logic and demonstrations, are the ones that attention should be paid to.

Unfortunately, this fast moving Internet medium of information exchange makes it difficult for the typical reader to detect and receive Serg’s and others signals in the noise.

Michael

Absolutely amazing, not one "I" in your entire post

 

[Regular Guy]

Date: 7/24/2007 12:22:04 PM
Author: Wink

Could you do us the honor of perhaps starting a separate thread that would show us both well cut, like the EightStar used here and a less well cut and perhaps even a poorly cut stone, so that we can experience more of the differences that cutting makes?

Wink

Here here!

 

[JohnQuixote]

Date: 7/24/2007 11:55:20 AM
Author: michaelgem

The noise has returned to Pricescope

All the deconstructive comments noise has made at the conclusion of this thread have already been addressed and answered with clear, constructive discussion, analogies and demonstrations. No need for further elaboration.

Any who care can reread what several have already eloquently stated and backed up with clear, constructive demonstrations.

Michael, in the interest of peace, I don't think Marty's statements are in conflict with anything that's been put forward. Sergey showed that different combinations can have equal appeal - and that color entrapment begins at a certain threshold. We all knew this (?)

Date: 7/22/2007 5:00:07 PM
Author: adamasgem

Date: 7/22/2007 3:02:34 PM
Author: adamasgem
1) 'People' talk about sweet spot, and equate geometric center for some grading paradigm, with optimal performance, which is flat wrong, and should be STOPPED

2) Any optimal performance 'spot' is a function of the lighting envirornment used, if X number of evaluators use X different environments they will come up with X different 'optimal' positions (or or facet combinations)

3) The optimal position of any performance metric is technically a function of the inherent absorption characteristics of the stone AND the SIZE of the stone, it is a very NON LINEAR process.

4) Within a very small BOX (as in a GIA or AGS paradigm) there are localized maxima and minima, it is not necessarily a smooth function, and we have shown that before.

I'll add that lighting INCLUDES the spectrum of the light, what might be optimal for NYC noon 'daylight' might not be as optimal for Miami 'noon' daylight, all other factors being equal.

Which goes to the point of someone here crowing about Henry Morse and 34/41.

SYMMETRIC Gas light vs SYMMETRIC incandescent vs SYMMETRIC flourescent vs some color temperature of 'SYMMETRIC' daylight will ALL give differing relative 'goodness' results, and 'look' to the diamond, subtle or maybe not subtle, on either an absorbing or non aborbing 'ideal' stone. Basic laws of physics.

Throw in assymetry in the lighting model or the stone and you can get radical changes, as shown long ago by tilting the stone.

You can design a stone to maximize anyones given metric for ANY SPECIFIC environment, especially when you throw in point sources where the aspect angle of the source relative to the stone can make serious changes in the perceived metric results.

This is healthy perspective. Conclusions like Morse vs Tolk vs Atlas vs Holloway vs Cowing differ, depending on whether you use charts, cut guides, software projections or actual grades - and lighting environment and symmetry must be considered.

Between you, the diamond cutters and Garry I think we would have three different (all attractive) "points" of great appeal. Which is right? None. Which is wrong? None.

PS: If you remove words like "crowing" and "noise" from the posts above they read better by the way.

 

[psadmin]

It seems the main discussion is completed. This thread is starting to get hijacked. Please start new thread for new discussion.

Thank You.
Andrey
PS Admin

 

[psadmin]

Michael -

"noise" is a relative measure and if your comments were directed to Adamas I would especially apperciate if you refrain from such in the future.

Thank You.
Andrey
PS Admin