AGS new cut grade system early 2005

[Garry H (Cut Nut)]

Marty I am glad you mentioned AGS in at least one of your posts. There is actully a seperate one on Fire and Dispersion that would probably have been a more appropriate place for your discussuions.

So to come back to the topic - would you care to comment on AGS's new cut grade system?
Why did they cease to continue to work with you and 8*?

Care to comment on my a stab in the dark at what I believe to be the format for their new system?

It is displayed on a chart in an earlier post on this thread.

BTW - Image adjusted so that all diamonds are close to the same size.

 

[adamasgem]

----------------
On 9/22/2004 9:51:58 PM goodpointz wrote:

Which one of the four images indicates the strongest dispersion? 1 and 3 seem to show the best symmetry, with 3 showing the most color, and 1 showing the most blue and black. Does any color = fire (i.e. more color means more dispersion) or do specific colors (i.e. blue and black) indicate different things? Very interesting photo! ----------------

My observations on the photos I have taken are:

The higher the level of optical symmetry the purer and more intense the spectral hues, lower the optical symmetry and the colors go to pastels or earth tones , they muddy up

The higher the level of optical symmetry the broader the areas of identical color, giving broadflash rather than pinfire to use the opal analogy. As a note, stone with broadflash fire are more distinctive and recognizable from a distance. What I think happens is that stones with small areas of color start to mix as you move away from the stone so the eye cannot resolve them as separate areas of color..

Off make stones just don't perform well at all, in terms of fire..

Afer I finish modeling the environment, I might understand what is going on better than I do now. One of the things I haven't done yet is read-in Sarin data files so I can build an a-symmetric stone model, but one of the problems that arises is that all the Sarin data on all the facets has to be self consistent, add up as a whole if you will, which I don't think it necessarily is, because of the inherent measurement errors.

The Sarin data book that a friend has indicates quoted accuracy of +/- 0.02mm and +/- 0.4 degrees error levels, but I understand the latest Sarin may be much better.. Sergey, can you comment on this??

 

[adamasgem]

----------------
On 9/22/2004 9:53:07 PM Garry H (Cut Nut) wrote:

Marty I am glad you mentioned AGS in at least one of your posts. There is actully a seperate one on Fire and Dispersion that would probably have been a more appropriate place for your discussuions.
I don't necessarily have the time for two threads but I'll take a look

So to come back to the topic - would you care to comment on AGS's new cut grade system?

I would, if I knew more than generalities about it

Why did they cease to continue to work with you and 8*?

I was on the cut grade task force and they disbanded it. Then I started work with 8*. I'm happily not concerned, nor privy to contract relationships between 8* and AGS, and I wouldn't comment even if I was

Care to comment on my a stab in the dark at what I believe to be the format for their new system?

As I said before or implied before, what you did it is a stab in the dark, and I see no usefullness on commenting on something that hasn't been publically defined yet

It is displayed on a chart in an earlier post on this thread.

I saw it and commented on what you did before, you may be comparing apples and oranges, so what's the point, neither you nor I know what lighting model they are using, nor do I know the specifics of the MSU model, only a generality about an indeterminate number of spot lights with some background



BTW - Image adjusted so that all diamonds are close to the same size.

Obviously Gary, what a brilliant observation, additionally, they were all reduced in jpeg resolution so I can post within the 100K limit

----------------

 

[Serg]

----------------
On 9/22/2004 7:08:12 PM adamasgem wrote:

This is why I'm spending my time trying to model what I can photograph, rather than playing with chromatic flares as a measure of Fire.

The composite photo is increased in saturation level for printing and display, from left to right,1) an EightStar, 2) a GIA EX/EX, 3) a branded, 1990's version of 'ideal', and 4) your typical mall store off make..

I think a picture is worth a thousand words..----------------

Marty,
I need some words too. Picture is not enough.

Did you use symmetrical(quasi-symmetrical) light?
What lens and diaphragm did you use ?
What is distance between diamond and lens, diamond and light.

About Sarin. Accuracy depends from field of view. I do not know why Sarin indicate one accuracy for all scanners. I believe New Sarin for 8-11 mm has better accuracy.

 

[adamasgem]

----------------
On 9/23/2004 2:21:04 AM Serg wrote:

----------------
On 9/22/2004 7:08:12 PM adamasgem wrote:

This is why I'm spending my time trying to model what I can photograph, rather than playing with chromatic flares as a measure of Fire.

The composite photo is increased in saturation level for printing and display, from left to right,1) an EightStar, 2) a GIA EX/EX, 3) a branded, 1990's version of 'ideal', and 4) your typical mall store off make..

I think a picture is worth a thousand words..----------------

Marty,
I need some words too. Picture is not enough.
In general, white light in, color out. Environment allows showing Fire./b>

Did you use symmetrical(quasi-symmetrical) light?
Yes Sergey, I've tried to eliminate all possibility of aliasing results. The 3D source modeling is not too difficult, but understanding why we see what we see, is a little complex, as is "quantifying" the results into a scaler metric, which I'm not really too willing to do, as I think a metric won't tell the story of the stone as well as a picture does.

What lens and diaphragm did you use ?
What is distance between diamond and lens, diamond and light.
Sorry, but this information is covered in the patent application which will be available once the USPTO (US Patent and Trademark Office) publishes it. Those who might know something are precluded contractually from disclosure, as there are too many copycats out there.

About Sarin. Accuracy depends from field of view. Yup

I do not know why Sarin indicate one accuracy for all scanners.
In the US, we call it the KISS principle: "Keep It Simple Stupid"

I believe New Sarin for 8-11 mm has better accuracy.
I understand they have a new camera and software which improves it

----------------

 

[Serg]

----------------
On 9/23/2004 10:22:46 AM adamasgem wrote:

----------------
On 9/23/2004 2:21:04 AM Serg wrote:

----------------
On 9/22/2004 7:08:12 PM adamasgem wrote:

This is why I'm spending my time trying to model what I can photograph, rather than playing with chromatic flares as a measure of Fire.

The composite photo is increased in saturation level for printing and display, from left to right,1) an EightStar, 2) a GIA EX/EX, 3) a branded, 1990's version of 'ideal', and 4) your typical mall store off make..

I think a picture is worth a thousand words..----------------

Marty,
I need some words too. Picture is not enough.
In general, white light in, color out. Environment allows showing Fire./b>

Did you use symmetrical(quasi-symmetrical) light?

Yes Sergey, I've tried to eliminate all possibility of aliasing results. The 3D source modeling is not too difficult, but understanding why we see what we see, is a little complex, as is 'quantifying' the results into a scaler metric, which I'm not really too willing to do, as I think a metric won't tell the story of the stone as well as a picture does.


----------------

Symmetrical light could be one of reasons why symmetrical stones has best Fire on your photo.

 

[adamasgem]

----------------
On 9/23/2004 11:05:59 AM Serg wrote:

----------------
On 9/23/2004 10:22:46 AM adamasgem wrote:

----------------
On 9/23/2004 2:21:04 AM Serg wrote:

----------------
Symmetrical light could be one of reasons why symmetrical stones has best Fire on your photo.
----------------

Sergey.. There is NEVER a truly symmetrical physical environment with respect to a stones symmetry, what you try to do is not potentially bias a result like using parallel rays from one overhead source, as used in the GIA Fire study.

Symmetry in the stone improves the purity/strength of the spectral hues, the colors are not muddy or pastels like in poorer makes. Not as much color mixing or combination of wave fronts, I think.

Fire also depends strongly on the overall cut (crown/pavillion) of the stones.. see picture 4 showing a dead stone.

There is a very strong correlation between overall AGS cut grade and Fire Performance picture visual quality. But I have seen AGS 3's with what I think is really good fire performance.

 

[adamasgem]

----------------
On 9/23/2004 11:05:59 AM Serg wrote:

----------------
On 9/23/2004 10:22:46 AM adamasgem wrote:

----------------
On 9/23/2004 2:21:04 AM Serg wrote:

----------------

Symmetrical light could be one of reasons why symmetrical stones has best Fire on your photo.
----------------

I would strongly suggest that highly symmetrical stones produce the best Fire, period, independent of environment. And that is based not only on visual observation, but photos. They certainly produce the best broadflash Fire, larger areas of the same color, allowing the human eye to resolve the Fire, it doesn't get lost. I'm sure you could agree with that, Sergey.
Of course Fire is also dependent on the facet angles.

 

[Serg]

----------------
On 9/23/2004 12:55:24 PM adamasgem wrote:

----------------
On 9/23/2004 11:05:59 AM Serg wrote:

----------------
On 9/23/2004 10:22:46 AM adamasgem wrote:

----------------
On 9/23/2004 2:21:04 AM Serg wrote:

----------------

Symmetrical light could be one of reasons why symmetrical stones has best Fire on your photo.
----------------

I would strongly suggest that highly symmetrical stones produce the best Fire, period, independent of environment. And that is based not only on visual observation, but photos. They certainly produce the best broadflash Fire, larger areas of the same color, allowing the human eye to resolve the Fire, it doesn't get lost. I'm sure you could agree with that, Sergey.
Of course Fire is also dependent on the facet angles.


----------------

I could agree with that for diamond less than 3 -5 ct only.

If you could prove it for 10 ct by used unsymmetrical light, I could agree.

your photo clearly shows that *8 diamond has resonance with light. It is not usually for usual light conditions

 

[adamasgem]

----------------
On 9/23/2004 1:11:51 PM Serg wrote:

----------------
On 9/23/2004 12:55:24 PM adamasgem wrote:

----------------


I would strongly suggest that highly symmetrical stones produce the best Fire, period, independent of environment. And that is based not only on visual observation, but photos. They certainly produce the best broadflash Fire, larger areas of the same color, allowing the human eye to resolve the Fire, it doesn't get lost. I'm sure you could agree with that, Sergey.
Of course Fire is also dependent on the facet angles.


----------------

I could agree with that for diamond less than 3 -5 ct only.
On what technical basis do you make that statement? Inquiring minds want to know. I'm really curious.

If you could prove it for 10 ct by used unsymmetrical light, I could agree.

Well, I DO KNOW that the 13ct American Star by EightStar displays a HELL of a lot of Fire, and in the real as-symetrical lighting environments I have seen it in.

your photo clearly shows that *8 diamond has resonance with light. It is not usually for usual light conditions

Not to get into an arguement, but how many 8*'s have you seen to back up your statement. One, if that? Look Sergey, "usual" lighting conditions in a jewelry store hide fire in probably every stone because they swamp out the stone with overly bright lighting, makes it almost impossible to distinguish one stone from another, so even GARBAGE looks good. It is sort of like trying to distinguish two diamonds apart if you are 20 feet away. Go to a nice restuarant with dimmer lighting and a well cut stone will display its Fire.

That's why I've been commenting and cautioning regarding the use of RayTrace results to quantify a stone's performance, especially when the environment used may or may not be realistic of a consumer's "normal" viewing conditions. And I doubt that the consumer wants an assessment of a diamond's performance in a typical Jewelry store's lighting.

Both MSU's and AGS's environments have have yet to be fully disclosed, to my knowledge, and GIA's uniform hemispherical lighting model is surely nothing like that found in nature, and may blurr the distinction between diamonds cutting.



----------------

 

[Serg]

----------------
On 9/23/2004 2:22:29 PM adamasgem wrote:

----------------
On 9/23/2004 1:11:51 PM Serg wrote:

----------------
On 9/23/2004 12:55:24 PM adamasgem wrote:

----------------


I would strongly suggest that highly symmetrical stones produce the best Fire, period, independent of environment. And that is based not only on visual observation, but photos. They certainly produce the best broadflash Fire, larger areas of the same color, allowing the human eye to resolve the Fire, it doesn't get lost. I'm sure you could agree with that, Sergey.
Of course Fire is also dependent on the facet angles.


----------------

I could agree with that for diamond less than 3 -5 ct only.
On what technical basis do you make that statement? Inquiring minds want to know. I'm really curious.

If you could prove it for 10 ct by used unsymmetrical light, I could agree.

Well, I DO KNOW that the 13ct American Star by EightStar displays a HELL of a lot of Fire, and in the real as-symetrical lighting environments I have seen it in.

your photo clearly shows that *8 diamond has resonance with light. It is not usually for usual light conditions

Not to get into an arguement, but how many 8*'s have you seen to back up your statement. One, if that? Look Sergey, 'usual' lighting conditions in a jewelry store hide fire in probably every stone because they swamp out the stone with overly bright lighting, makes it almost impossible to distinguish one stone from another, so even GARBAGE looks good. It is sort of like trying to distinguish two diamonds apart if you are 20 feet away. Go to a nice restuarant with dimmer lighting and a well cut stone will display its Fire.

That's why I've been commenting and cautioning regarding the use of RayTrace results to quantify a stone's performance, especially when the environment used may or may not be realistic of a consumer's 'normal' viewing conditions. And I doubt that the consumer wants an assessment of a diamond's performance in a typical Jewelry store's lighting.

Both MSU's and AGS's environments have have yet to be fully disclosed, to my knowledge, and GIA's uniform hemispherical lighting model is surely nothing like that found in nature, and may blurr the distinction between diamonds cutting.



----------------

----------------

Re: "On what technical basis do you make that statement? Inquiring minds want to know. I'm really curious."

It is very long story. I am ready to discuss it with you on Forum, but firstly I suggest you to study report and posters, which we have made at Moscow IDCC on April, 2004. This will essentially reduce your and my time spending. These materials have already published in Conference Proceedings and have already sent to Conference participants (2 pcs for every participant). Also sooner it will be possible to order them from Garry Holloway.


Re: "Well, I DO KNOW that the 13ct American Star by EightStar displays a HELL of a lot of Fire, and in the real as-symetrical lighting environments I have seen it in. "

I don't doubt that 13ct American Star has much of fire, but how you conclude from this that other 13ct diamond can't have more Fire?
Why photos you got with help of symmetrical lighting can be proof that symmetrical stones under unsymmetrical lighting will have the same advantage?
Why you put "typical mall store off make" as unsymmetrical stone with wittingly bad parameters (Pav. angle=42.3-42.8 and Lower Facet=85-87%) for comparison?
Where are actually scientific arguments? May be it doesn't make sense to call tricks as science?

By the way, did I say ever that *8 is bad stone or it has less Fire?
I think that *8 actually has much of Fire, but MAIN reason of this fact is not supersymmetry. The more important reason is right value of Lower Facet height (of course with corresponding right angles of crown and pavilion).

Other hypothesis is: H&A diamond with Lower Facet=75-78% will have more Fire than *8 Diamond with Lower Facet=85%.

Is it reasonable hypothesis?


Re: Not to get into an arguement, but how many 8*'s have you seen to back up your statement. One, if that?

Marty, do you really need to know how many *8 diamonds author of these statements have seen to estimate correctness of statements?

I don't think that surplus lighting which is very often used in a jewellery store is the lighting which is used by consumer when he demonstrates jewellery ware to other people (although this lighting should be modelled and considered too).
What lighting you can distinguish two *8 of the same diameter from distance 30-50 cm? ) Where is this nice restaurant with dimmer lighting to distinguish Fire from two *8 diamonds?

By the way, I have only one Firescope, and you think that this is serious restriction for me to understand how it works?

 

[adamasgem]

----------------
On 9/24/2004 11:35:59 AM Serg wrote:

----------------

Re: 'On what technical basis do you make that statement? Inquiring minds want to know. I'm really curious.'

It is very long story. I am ready to discuss it with you on Forum, but firstly I suggest you to study report and posters, which we have made at Moscow IDCC on April, 2004. This will essentially reduce your and my time spending. These materials have already published in Conference Proceedings and have already sent to Conference participants (2 pcs for every participant). Also sooner it will be possible to order them from Garry Holloway.

Since I didn't have the monies to attend the conference, and since I understand that the AGS presentation won't be released as part of it, I didn't order one from Gary. Perhaps you would be kind enough to send me a pdf, for educational purposes, and then we can discuss it here.

Re: 'Well, I DO KNOW that the 13ct American Star by EightStar displays a HELL of a lot of Fire, and in the real as-symetrical lighting environments I have seen it in. '

I don't doubt that 13ct American Star has much of fire, but how you conclude from this that other 13ct diamond can't have more Fire?

I didn't say that Serg, you said a stone over 10ct couldn't have Fire, if I read you right, that's why I questioned the statement. If I misread your statement "If you could prove it for 10 ct by used unsymmetrical light, I could agree" then I apologise

Why photos you got with help of symmetrical lighting can be proof that symmetrical stones under unsymmetrical lighting will have the same advantage?

Sergey, As I said before, there is no truly symmetrical lighting, I try to make it symmetrical so as to not alias the results. What sense does it make to base a decision on how well a stone will perform under a light coming from 45 degees or only parallel rays perpendicular to the table, or only five sources at some fixed, unpublished angles, like the MSU study. PS: Try looking at thousands of sources

Why you put 'typical mall store off make' as unsymmetrical stone with wittingly bad parameters (Pav. angle=42.3-42.8 and Lower Facet=85-87%) for comparison?

I put it there as an example because it is not atypical of what is sold out there by a lot in the trade, and you know that as well as I do, and I've got plenty more, which show a progressive degradation in performance which somewhat correlates with AGS cut grade. There are exceptions to the rule, depending on what factor sets the cut grade.

Where are actually scientific arguments? May be it doesn't make sense to call tricks as science?

BULLS**T Serg, I'll take BIG exception to that statement, very unprofessional, NO tricks, just plain photos, all taken in a controlled environment which emulates as best I can, a natural condition readily available to anyone.

By the way, did I say ever that *8 is bad stone or it has less Fire?
I think that *8 actually has much of Fire, but MAIN reason of this fact is not supersymmetry. The more important reason is right value of Lower Facet height (of course with corresponding right angles of crown and pavilion).

I really can't answer that regarding Fire, I know the improvements EightStar cutting makes to general light return, but I have seen "Normal" GIA ex/ex with very good Fire. If you say that EightStars have more Fire because of the subtle way they are cut, who am I to disagree with you

(Really I'm not trying to promote EightStar here, only high quality cutting) I think that stones which are assymetrical, or let's say simply misaligned table to crown, break up the areas of any Fire into smaller pieces of color much less resolvable and distinct to the human eye. You must know that from your work, I believe; the "contrast" pattern breaks down, I think that you can show that with your EXCELLENT DiamondCalc software. Since I haven't bought the latest updates to your software I don't know whether you can do that or not.

Other hypothesis is: H&A diamond with Lower Facet=75-78% will have more Fire than *8 Diamond with Lower Facet=85%.

Is it reasonable hypothesis?

As I say, I can't really comment on the Fire aspect of one cut versus another yet, because I haven't decided how to address it in my software

Re: Not to get into an arguement, but how many 8*'s have you seen to back up your statement. One, if that?

Marty, do you really need to know how many *8 diamonds author of these statements have seen to estimate correctness of statements?

Well, it was a legitimate question as to the basis of your statements

I don't think that surplus lighting which is very often used in a jewellery store is the lighting which is used by consumer when he demonstrates jewellery ware to other people (although this lighting should be modelled and considered too).
I think bright jewelry store lighting may mislead consumers

What lighting you can distinguish two *8 of the same diameter from distance 30-50 cm? ) Where is this nice restaurant with dimmer lighting to distinguish Fire from two *8 diamonds?

Practically any environment that doesn't blast you out with overall intense light will do. In your home, for one, maybe a candle-lit dinner, point sources in a dim background really shows Fire off

By the way, I have only one Firescope, and you think that this is serious restriction for me to understand how it works?----------------

OK, Serg, I guess one will do there, so now maybe you can explain some concepts and misconceptions regarding the Firescope to a mutual friend

 

[Serg]

----------------
On 9/24/2004 5:23:24 PM adamasgem wrote:

----------------
On 9/24/2004 11:35:59 AM Serg wrote:

----------------

I think that *8 actually has much of Fire, but MAIN reason of this fact is not supersymmetry. The more important reason is right value of Lower Facet height (of course with corresponding right angles of crown and pavilion).

Sergey:I really can't answer that regarding Fire, I know the improvements EightStar cutting makes to general light return, but I have seen 'Normal' GIA ex/ex with very good Fire. If you say that EightStars have more Fire because of the subtle way they are cut, who am I to disagree with you

(Really I'm not trying to promote EightStar here, only high quality cutting) I think that stones which are assymetrical, or let's say simply misaligned table to crown, break up the areas of any Fire into smaller pieces of color much less resolvable and distinct to the human eye. You must know that from your work, I believe; the 'contrast' pattern breaks down, I think that you can show that with your EXCELLENT DiamondCalc software. Since I haven't bought the latest updates to your software I don't know whether you can do that or not.

Other hypothesis is: H&A diamond with Lower Facet=75-78% will have more Fire than *8 Diamond with Lower Facet=85%.

Marty:Is it reasonable hypothesis?

b]

See below images.
All for classical round 57. I did not check modification of azimuth for crown girdle facets.


Pav. angle=40.55
Crown angle=34.50
Lower facets=74%


----------------

 

[Serg]

Pav. angle=40.55
Crown angle=34.50
Lower facets=78%

 

[Serg]

Pav. angle=40.55
Crown angle=34.50
Lower facets=82%

 

[Serg]

BUT


Pav. angle=40.55
Crown angle=35.50
Lower facets=78%

 

[Bagpuss]

The first and last pics are a fairy wonderland of colour. That's the kind of fire we all want from a diamond.

 

[adamasgem]

----------------
On 9/26/2004 10:23:23 AM Serg wrote:

----------------
See below images.
All for classical round 57. I did not check modification of azimuth for crown girdle facets.


Pav. angle=40.55
Crown angle=34.50
Lower facets=74%


----------------

----------------

Sergey.. Yes, your very good illustrations show what appear to be higher chromatic flares for the shorter breaks, BUT

1) I believe they are for a "theoretical" parallel source perpendicular to the table: what about other light rays hitting the stone?..how about a realistic "total" environment..

2) The high dispersion you show seems to be coming out toward the low angle side of the hemisperical dome whereas the viewer is typically normally "looking down" on the top of the dome, facing the table..

Will the viewer ever "see" these areas of high dispersion??? That's why I'm a little leary of these type of "analyses". Don't get me wrong, they are good exercises, but what are they really telling you about the stone will do in a "real" environment, I haven't been convinced.

 

[Serg]

----------------
On 9/26/2004 1:26:53 PM adamasgem wrote:


Sergey.. Yes, your very good illustrations show what appear to be higher chromatic flares for the shorter breaks, BUT

1) I believe they are for a 'theoretical' parallel source perpendicular to the table: what about other light rays hitting the stone?..how about a realistic 'total' environment..

2) The high dispersion you show seems to be coming out toward the low angle side of the hemisperical dome whereas the viewer is typically normally 'looking down' on the top of the dome, facing the table..

Will the viewer ever 'see' these areas of high dispersion??? That's why I'm a little leary of these type of 'analyses'. Don't get me wrong, they are good exercises, but what are they really telling you about the stone will do in a 'real' environment, I haven't been convinced.


----------------

1) No . I use cone beam tracing. Angle depends from pupil , distance from pupil to table and size of table.
2) No. It is all for "mono-typically" viewer

I showed for 10 mm light source main( not for dark room) positions when viewer with 5 mm pupil will see flash. Position center of light define color of flash.( Point flash on hemisphera color define of flash in eye)

other words it* is "average" quantity of flash is observed by viewer

* surface flash on hemisphere

 

[adamasgem]

----------------
On 9/26/2004 2:38:25 PM Serg wrote:

----------------
On 9/26/2004 1:26:53 PM adamasgem wrote:


Sergey.. Yes, your very good illustrations show what appear to be higher chromatic flares for the shorter breaks, BUT

1) I believe they are for a 'theoretical' parallel source perpendicular to the table: what about other light rays hitting the stone?..how about a realistic 'total' environment..

2) The high dispersion you show seems to be coming out toward the low angle side of the hemisperical dome whereas the viewer is typically normally 'looking down' on the top of the dome, facing the table..

Will the viewer ever 'see' these areas of high dispersion??? That's why I'm a little leary of these type of 'analyses'. Don't get me wrong, they are good exercises, but what are they really telling you about the stone will do in a 'real' environment, I haven't been convinced.


----------------

1) No . I use cone beam tracing. Angle depends from pupil , distance from pupil to table and size of table.
But is the Cone Beam a parallel source, as your pics suggest

2) No. It is all for 'mono-typically' viewer

I showed for 10 mm light source main( not for dark room) positions when viewer with 5 mm pupil will see flash. Position center of light define color of flash.( Point flash on hemisphera color define of flash in eye)

other words it* is 'average' quantity of flash is observed by viewer

* surface flash on hemisphere

But the viewer doesn't "see" what you suggest, becuase he is not looking at the backside of a hemisphere. Your pictures are like GIA's "Fire" pics, who cares what happens in an unrealistic environment, if it is not telling you what happens in "real" life. Respectfully, that is my main hangup with both what I believe you and GIA, as well as what AGS published in the optics article./b>

----------------

 

[Garry H (Cut Nut)]

Marty to save Sergey answering all your questions again - read the Fire discussion that I linked you to earlier in the thread.

 

[Serg]

Sergey:"Re: No . I use cone beam tracing. Angle depends from pupil , distance from pupil to table and size of table."
Marty:"But is the Cone Beam a parallel source, as your pics suggest "

It follows just from my pics, that we do not work with parallel source. How parallel source can get white zones at distant sphere, but only after reflection from diamond surface?


Mary: "Re: But the viewer doesn't "see" what you suggest, becuase he is not looking at the backside of a hemisphere. "

Marty, with all my respect to you, I think that you don't know how to use "Back Ray tracing" tool at full capacity.

I suggest you firstly investigate what in "Back Ray tracing" is useful, and then to read my discussions with Bruce Harding about ray reversibility and color reversibility on DT and PS forums, and only after that to return to the interpretation of my pics.

While we have pause on this theme, I suggest to investigate one your statements which I was very interested.

Sergey :"What lighting you can distinguish two *8 of the same diameter from distance 30-50 cm? ) Where is this nice restaurant with dimmer lighting to distinguish Fire from two *8 diamonds?"

Marty: "Practically any environment that doesn't blast you out with overall intense light will do. In your home, for one, maybe a candle-lit dinner, point sources in a dim background really shows Fire off"

Did I understand correctly that:

You are ready to point out two *8 diamonds with equal weight which you can surely distinguish by conditions you indicated?

As I understand, identification with simultaneous demonstration is more simple than with a consecutive demonstration. So I suggest you the following method.

You choose good* restaurant (with smoking prohibition) and somebody shows you two diamonds. We investigate them carefully, number them as "1st" and "2nd" by noting their laser inscriptions on girdles.

Then I remove stones, mix them and give them to you again. You should determine what stone is "1st" keeping them at the distance not less than 30cm and using tweezers only.

An experiment controler** and 1-2 test observers try to distinguish the same stones (I want to understand who else can distinguish them - in the case of your winning). We repeat procedure 12 times, and if you are right 10 or more out of 12, then you win. If less then you have lost.***

*Not restaurant of fast food and bad wine please.
**If you agree, I will try to come to you, or one of my partners or friends will do it.
***It is simple to guess 5-7 times using coin as analyzer. To guess 10-12 times is very hard (2%). The loser will pays for dinner.

P.S. If you will agree to take part in this experiment, can you prepare two stones 0.8ct weight. I plan to purchase one of them for Master Stone Set, but in the case of you winning I should revise the budget and purchase both stones.

 

[adamasgem]

----------------
On 9/27/2004 5:53:08 AM Serg wrote:






Sergey:'Re: No . I use cone beam tracing. Angle depends from pupil , distance from pupil to table and size of table.'
Marty:'But is the Cone Beam a parallel source, as your pics suggest '

It follows just from my pics, that we do not work with parallel source. How parallel source can get white zones at distant sphere, but only after reflection from diamond surface?


Sergey We have a language translation problem here, but you are doing MUCH better than I would do in Russian. It seems to me that you are using a "cone" or ray of light coming in perpendicular to the table to generate the chromatic dispersion pics, similar to GIA's Fire model.

Mary: 'Re: But the viewer doesn't 'see' what you suggest, becuase he is not looking at the backside of a hemisphere. '

Marty, with all my respect to you, I think that you don't know how to use 'Back Ray tracing' tool at full capacity.

I probably don't, but still, would you define the "source" to generate the pics


Sergey :'What lighting you can distinguish two *8 of the same diameter from distance 30-50 cm? ) Where is this nice restaurant with dimmer lighting to distinguish Fire from two *8 diamonds?'

Marty: 'Practically any environment that doesn't blast you out with overall intense light will do. In your home, for one, maybe a candle-lit dinner, point sources in a dim background really shows Fire off'

Did I understand correctly that:

"You are ready to point out two *8 diamonds with equal weight which you can surely distinguish by conditions you indicated?"

No (mis interpretation problem here), what I meant was distinguishing an 8* (or other similiar well cut stone) from a typically cut stone, with lower symmetry. I KNOW I couldn't pick out two 8*'s of the same size from one another under the conditions you describe [but I'd be happy to spring for dinner anyway

]


----------------

 

[Serg]

re:I probably don't, but still, would you define the "source" to generate the pics

Are you asking about the light source or the software source?

 

[Serg]

Re:Marty: " Sergey We have a language translation problem here, but you are doing MUCH better than I would do in Russian. It seems to me that you are using a "cone" or ray of light coming in perpendicular to the table to generate the chromatic dispersion pics, similar to GIA's Fire model."

Evidently We should write detailed article about tools "BackRayTracing" and "BackConeTracing". I will try to do this work without big delay.


Re:Marty :" I KNOW I couldn't pick out two 8*'s of the same size from one another under the conditions you describe "

Marty,

If you know that two *8 diamonds cannot be distinguished by unaided eye, then why your question :
"Not to get into an arguement, but how many 8*'s have you seen to back up your statement. One, if that?"

can be considered as
"Well, it was a legitimate question as to the basis of your statements"

?

 

[Serg]

pav= 40.7
Crown= 34.9
LFacet=75%
Starfacet=60%

Azimuth of upper girdle facets was changed by 6 degrees. ( like *8star)

Do you see new Fire circle?

That is real reasons of new Fire?( All diamonds is symmetrical)

 

[Garry H (Cut Nut)]

Marty will want to know how many reflections have been calculated Sergey?

Do more reflections mean more fire, or does more light return mean more washed out fire?

 

[adamasgem]

----------------
On 9/28/2004 5:40:10 AM Serg wrote:

pav= 40.7
Crown= 34.9
LFacet=75%
Starfacet=60%

Azimuth of upper girdle facets was changed by 6 degrees. ( like *8star)

Do you see new Fire circle?

That is real reasons of new Fire?( All diamonds is symmetrical)----------------

Sergey .. (I think so) but with all due respect, what am I comparing this picture against?
You haven't shown a pic with the same basic facet angles with a baseline upper girdle, such that I can make a logically reasoned comment.

Same Table/Crown/pavilion/star/lower girdle +/- upper girdle change

What I am trying to figure out is in my pics is the why for the better the optical symmetry, the purer the hues with more broadflash. I don't think the chromatic flare simulations answer that question

 

[Serg]

----------------
On 9/28/2004 12:46:46 PM adamasgem wrote:

----------------
On 9/28/2004 5:40:10 AM Serg wrote:

pav= 40.7
Crown= 34.9
LFacet=75%
Starfacet=60%

Azimuth of upper girdle facets was changed by 6 degrees. ( like *8star)

Do you see new Fire circle?

That is real reasons of new Fire?( All diamonds is symmetrical)----------------

Sergey .. (I think so) but with all due respect, what am I comparing this picture against?
You haven't shown a pic with the same basic facet angles with a baseline upper girdle, such that I can make a logically reasoned comment.

Same Table/Crown/pavilion/star/lower girdle +/- upper girdle change

What I am trying to figure out is in my pics is the why for the better the optical symmetry, the purer the hues with more broadflash. I don't think the chromatic flare simulations answer that question----------------

re: Same Table/Crown/pavilion/star/lower girdle +/- upper girdle change

You are right. I will do it tomorrow.

re: What I am trying to figure out is in my pics is the why for the better the optical symmetry, the purer the hues with more broadflash.

I think You could see this phenomena only If you use a lot of small sources light at the same time .

Asymmetrical diamond produce much more possibility to see small light source . This and because size of image of light source could more then size of virtual facet are reason why in one point you could see light from different light sources.
If you use normal quantity of light source this phenomena is very rare( impossible)

 

[Serg]

I hope this diamond has same parameters except upper girdle facets.