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41 degree pavillion angle

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Thanks Ellen, Aljdewey and Lop. Working Hard - wouldn't mind going to look at lots of diamonds but not able to at the moment unfortunately. I think a part of the reason I said I didn't love the stone was because I was not used to the smaller table size compared to 57.5 or larger tables and as the table is smaller the pavillion by comparison looks smaller through the table and seemed to give me the illusion of being deeper and what I was callilng cone like whereas a large table you see more of the pavillion on show through the table area, I think this is what I was seeing as something I did not love and attributing it wrongly in my mind to the 41 degree pavillion angle which I already had doubts about from information I had read on the forum (not from Whiteflash).

Now I think I know it is the table it doesn't bother me the same so it was a mind clean thing. I have looked at Pricescopers diamonds and lots of them bought from Whiteflash and I see this same what I was describing as cone look but now I am used to it I don't see it as that anymore but just as a smaller table. So it is my perception of how diamonds looked with larger tables that was confusing me, either that or I am thinking that maybe larger diamonds show a larger crown area around the table. I knew before I got the diamond it would probably have a smaller table but the 41 pavillion angle took over and put that out of my mind.


I did though after Brian the Cutter posted ask Jonathan a question by email and he knew I was hesitating on the diamond and I do put faith in what Brian writes as I do the other experts/Scientists here. I read that he had written that I was weighing heavily Brian's words right after that email so that was just Jonathan reporting it as it was.
As I have mentioned before though the images Brian posted with the rough diamond showing the Tolkowsky diamond is not cut to save rough, what do people think about that, I have seen images similar to that before on the internet, and I always thought that was educating consumers about how a well cut diamond is judged because it was cut without trying to save weight? I know cutters do cut to save weight as I have read that for years too. So are the scientists not in agreement with that diagrams?
 
re:As I have mentioned before though the images Brian posted with the rough diamond showing the Tolkowsky diamond is not cut to save rough, what do people think about that, I have seen images similar to that before on the internet, and I always thought that was educating consumers about how a well cut diamond is judged because it was cut without trying to save weight? I know cutters do cut to save weight as I have read that for years too. So are the scientists not in agreement with that diagrams?

These Brian images have critical mistakes and too far from realty. But of course if you will increase pavilion angle you usually can increase yield. ( Sometimes you should decrease pavilion to increase yield due flat rough, inclusions, big tilt)

Strmrdr,
I will try do it latter.
Should work a little bit
 
As a cutter I would wish the octahedrons would look like this..., unfortunately the natural plane of the rough is more around 50 degrees plus! And not 41 degrees as these images convey.
weight41plus.jpg

Sergey wrote: These Brian images have critical mistakes and too far from realty. But of course if you will increase pavilion angle you usually can increase yield. ( Sometimes you should decrease pavilion to increase yield due flat rough, inclusions, big tilt)

I imagine these are the mistakes you are talking about...
 
Date: 7/16/2007 6:14:32 AM
Author: Serg
re:As I have mentioned before though the images Brian posted with the rough diamond showing the Tolkowsky diamond is not cut to save rough, what do people think about that, I have seen images similar to that before on the internet, and I always thought that was educating consumers about how a well cut diamond is judged because it was cut without trying to save weight? I know cutters do cut to save weight as I have read that for years too. So are the scientists not in agreement with that diagrams?

These Brian images have critical mistakes and too far from realty. But of course if you will increase pavilion angle you usually can increase yield. ( Sometimes you should decrease pavilion to increase yield due flat rough, inclusions, big tilt)

Strmrdr,
I will try do it latter.
Should work a little bit
Pyramid,

BTW 41/34/57 has less weight than 40.75/34.5/57 with same diameter. You can not win yeild in first diamond, you can win in mass second diamond( because diameter second ( smalest)diamond will bigger due lest crown height. See Brain images. :)
 
Thanks Serg.

I just want to make it clear I was not questionning Brian''s images as I am not an authority to do so but was just saying I had seen others not the same but in the same style on other internet sites showing a well cut diamond inside an octahedron and then showing another image the same style next to it with a diamond with thick girdle, large table, large pavillion as not well cut.
 
re:unfortunately the natural plane of the rough is more around 50 degrees plus!

I think like 54.75( do not remember exactly )

You can find other mistakes in these Brain images too. But he correctly showed idea why second diamond could has bigger diameter( best combitation for yeild in ideal rough is steep-deep(for first) +shalow-deep( for second)
 
Date: 7/16/2007 6:44:13 AM
Author: Serg
re:unfortunately the natural plane of the rough is more around 50 degrees plus!

I think like 54.75( do not remember exactly )

You can find other mistakes in these Brain images too. But he correctly showed idea why second diamond could has bigger diameter( best combitation for yeild in ideal rough is steep-deep(for first) +shalow-deep( for second)
I agree...

Yes, it seems like the crown angles on two of the images resembles -45deg- and not 35+/-...,
 
First 1.45 ct P41C35T55.6
Second 0.30 ct P41C35T60
But you also receive here
First 1.47 ct P41C35T53
Second 0.28 ct P41C35T60

And this example is far from real life too .Real game is much more complex. It is not for PS, Sorry

RoughIdeal3_29ct.GIF
 
Date: 7/16/2007 7:49:20 AM
Author: Serg
First 1.45 ct P41C35T55.6
Second 0.30 ct P41C35T60
But you also receive here
First 1.47 ct P41C35T53
Second 0.28 ct P41C35T60

And this example is far from real life too .Real game is much more complex. It is not for PS, Sorry
Agreed..., Much, much more complex!!!
Whats with the crown height Serg???

 

RE: BTW 41/34/57 has less weight than 40.75/34.5/57 with same diameter. You can not win yeild in first diamond, you can win in mass second diamond( because diameter second ( smalest)diamond will bigger due lest crown height. See Brain images. :)
Sergey Sivovolenko
CEO OctoNus
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


Serg,
Why doesn''t the increase in pav % of the first diamond create a similar experience as the crown % increase does in the second diamond. I submit that it weight retention would favor diamond #1 (41/24/57) because of it.

No need to answer as this is off the subject.

Bill Bray
Diamond Cutter

 
Date: 7/16/2007 6:40:18 AM
Author: Pyramid
Thanks Serg.

I just want to make it clear I was not questionning Brian''s images as I am not an authority to do so but was just saying I had seen others not the same but in the same style on other internet sites showing a well cut diamond inside an octahedron and then showing another image the same style next to it with a diamond with thick girdle, large table, large pavillion as not well cut.
Dont worry..., we didnt think you were...
Were just having a bit fun...
 
Date: 7/16/2007 7:49:20 AM
Author: Serg
First 1.45 ct P41C35T55.6
Second 0.30 ct P41C35T60
But you also receive here
First 1.47 ct P41C35T53
Second 0.28 ct P41C35T60

And this example is far from real life too .Real game is much more complex. It is not for PS, Sorry
7.30 mm Diameter? Just a guess...
 
Date: 7/16/2007 7:54:02 AM
Author: DiaGem

Date: 7/16/2007 7:49:20 AM
Author: Serg
First 1.45 ct P41C35T55.6
Second 0.30 ct P41C35T60
But you also receive here
First 1.47 ct P41C35T53
Second 0.28 ct P41C35T60

And this example is far from real life too .Real game is much more complex. It is not for PS, Sorry
Agreed..., Much, much more complex!!!
Whats with the crown height Serg???

I gave table. If you want I can add height

First 1.45 ct P41C35T55.6h15.5
Second 0.30 ct P41C35T60h14
But you also receive here
First 1.47 ct P41C35T53h16.5
Second 0.28 ct P41C35T60h14
 
Date: 7/16/2007 8:02:14 AM
Author: DiaGem

Date: 7/16/2007 7:49:20 AM
Author: Serg
First 1.45 ct P41C35T55.6
Second 0.30 ct P41C35T60
But you also receive here
First 1.47 ct P41C35T53
Second 0.28 ct P41C35T60

And this example is far from real life too .Real game is much more complex. It is not for PS, Sorry
7.30 mm Diameter? Just a guess...
7.257mm
Of course Princess 2Ct 7.228 mm is better for ideal crystal rough 3.29ct
 
Date: 7/16/2007 8:09:22 AM
Author: Serg

Date: 7/16/2007 8:02:14 AM
Author: DiaGem


Date: 7/16/2007 7:49:20 AM
Author: Serg
First 1.45 ct P41C35T55.6
Second 0.30 ct P41C35T60
But you also receive here
First 1.47 ct P41C35T53
Second 0.28 ct P41C35T60

And this example is far from real life too .Real game is much more complex. It is not for PS, Sorry
7.30 mm Diameter? Just a guess...
7.257mm
Of course Princess 2Ct 7.228 mm is better for ideal crystal rough 3.29ct
Yes, as long as all four corners are alive!
 

I think a part of the reason I said I didn't love the stone was because I was not used to the smaller table size compared to 57.5 or larger tables and as the table is smaller the pavillion by comparison looks smaller through the table and seemed to give me the illusion of being deeper and what I was calling cone like whereas a large table you see more of the pavillion on show through the table area, Now I think I know it is the table it doesn't bother me the same so it was a mind clean thing. Pyramid




Pyramid,




Please take a minute to check out my one page article on an expanded version of what diamond cutters call the eye in the diamond.




http://www.acagemlab.com/articles/DiamondEye.htm




If you have not already, you will reach a comfort level with the reflection pattern of your super ideal cut diamond. What is explained here are bare minimums for a diamond to be considered Ideal or Excellent cut by GIA, AGS, myself, and Ideal manufacturers like Eurostar or Lazar Kaplan and most Ideal cutters like the two I have referenced in the other article.




The most important thing to notice in this pattern is that the reflection of the table, which is the pupil of the eye, is roughly 1/3 the diameter of the table or iris. It should never be greater than half the table or one quarter the diamond diameter, because this upsets the distribution and balance of the brilliance and contrast that characterize Ideal.




As the table reflection "dilates" with pavilion angles significantly greater than 41, it not only upsets this balance of beauty, but this inner ring of reflections also rises giving the illusion of a flatter/shallower look to the diamond. By contrast, your ideal cut diamond has the illusion that you mention of greater depth. This is something that a female client of mine keyed on and said she loved because it seemed to draw her into the depth of its beauty.




Also your table is right in the heart of the sweet spot for table %. Had it been noticeably greater than 60% Ideal cutters would have jumped all over it as failing Ideal.




So this little one page article on the eye of the diamond reduces a ton of diamond cutting knowledge and understanding to its simplest form. Incidentally, diamond courses such as that taught by GIA, teach novice gemologists to use this table reflection to estimate quite accurately the pavilion angle, and cutters in past times used it to guide them in cutting to 41 degrees.




All the best to you,




Michael
 
Date: 7/16/2007 4:21:39 AM
Author: strmrdr
Serg,
Can you change the lgf% from 75% to 80% keeping the c/p combo the same and post the average light path for 41/34 and 40.75/34.5 for each?
I would be very interested in seeing the results.
40.75/34.5/57/82 -1.355
40.75/34.5/57/75 -1.362

41/34/57/82 -1.389
41/34/57/75 -1.452
 
In reply to Sarah''s inquiry about relationship to the eye and consumer I post the following synopsis in reply to the graphic used by QJohn. I used his graphic limiting the AGS 0 range because when I ran the range of scores on Michael''s it really didn''t make sense.

Since BrayScore uses the Tolkowsky based theoretical targets of the two parameters being discussed here (pav degree and crown degree) it was easy to assign scores to the sweetspots and sweetspot ranges.

Actual BrayScore utilizes the 16 top and bottom main measurements (rather than averages used in both lab systems and model construction) in addition to 58 other measurements directly related to the efforts of the cutter.

It takes approximately 3 seconds for the BrayScore webplatform to complete an analysis on a Sarin file. Other measurement systems wanting to be able to convert should contact our office.

BrayScore is the only cut grade system to date worthy of a US Patent.


Tolkowsky 40.75/34.5 = BrayScore 1000

Morse 41/35 = BrayScore 934

AGS Sweetspot 41.2/34 = BrayScore 920
AGS Sweetspot Range A 40.4/37.5 = BrayScore 848
AGS Sweetspot Range B 41/33 = BrayScore 916

GIA Sweetspot 41.2/34 = BrayScore 940
GIA Sweetspot range A 41.6/31.5 = BrayScore 808
GIA Sweetspot range B 40.6/36 = BrayScore 924

Highest BrayScore to date = BrayScore 935


Respectfully submitted

Bill Bray
Diamond Cutter


"when we rely on our senses for perception, there is no absolute"

- Tao philosophy
 
Is the second diagram on Brian''s images of Shallow/Deep a 34/41 stone?
 
michaelgem

I have read the eye article and will read it again. I know it is not half the table but not sure about third or quarter will have to look. Ofcourse as it is AGS0 it should be third.
 
Date: 7/16/2007 10:29:02 AM
Author: Pyramid
michaelgem

I have read the eye article and will read it again. I know it is not half the table but not sure about third or quarter will have to look. Ofcourse as it is AGS0 it should be third.
Pyramid,

Just as you should not get hung up on one exact combination of pavilion/crown angles, do not be concerned if the pupil/table reflection is not exactly one-third. A true Tolkowsky Ideal (P40.75 Cr34.5 T53), for example, has a 27.4%, not a 33%, table reflection due to its smaller table and resulting heavier crown / greater total depth.

Just as there is a sweet spot range for pavilion/crown angle combinations, there is a range or sweetspot of Ideal pupil sizes. This range is roughly centered at one-third.

Pupil sizes greater than one-half the table diameter or one quarter the diamond diameter are clearly outside this sweet spot, and such diamonds are not considered Ideal.

Again, your diamond is in the heart of the sweet spot in all the dimensions that have been addressed.

Ideal regards,

Michael
 
Thanks Michaelgem. Yes it looks like the first picture for the Ideal in your article.
 
Date: 7/16/2007 10:05:47 AM
Author: Serg

Date: 7/16/2007 4:21:39 AM
Author: strmrdr
Serg,
Can you change the lgf% from 75% to 80% keeping the c/p combo the same and post the average light path for 41/34 and 40.75/34.5 for each?
I would be very interested in seeing the results.
40.75/34.5/57/82 -1.355
40.75/34.5/57/75 -1.362

41/34/57/82 -1.389
41/34/57/75 -1.452
Thanks Serg, kewl info.
 
Date: 7/16/2007 10:24:54 AM
Author: Pyramid
Is the second diagram on Brian''s images of Shallow/Deep a 34/41 stone?
see Sergs image above, using the full rough for the pavilion would get you ~50 degrees from what DiaGem said and Serg''s image shows.
 
Date: 7/16/2007 11:31:22 AM
Author: strmrdr


Date: 7/16/2007 10:24:54 AM
Author: Pyramid
Is the second diagram on Brian's images of Shallow/Deep a 34/41 stone?
see Sergs image above, using the full rough for the pavilion would get you ~50 degrees from what DiaGem said and Serg's image shows.
Yes, thanks Storm. I was wondering though, in not real measurements, is that what it is meant to represent as in on the forum diamonds are referred to as shallow/deep and steep/deep although still in the Ideal range? I assume it is and that is why Brian posted it in the discussion. What I mean is he wasn't showing something like 32/45 or 38/46 (made up numbers, I have no clue they probably wouldn't be used together).
 
Wow guys. I go away for 6 pages and look what happens?

Picasso

I apologize my drawings are not going to make it to The Louvre or Metropolitan Museum of Art. :) I’ll leave it to the scientists to do graphic models. My intent at the start of the thread was to show in a simple way how cutting deep increases yield. Now that other professionals are here I welcome your improved graphics. I’m used to being spoiled in South Africa with a greater consistency of more regular sawable models, unlike the rest of the world having to deal with more difficult mixes, hence my simple octahedral illustration. Sorry guys - like I said I’m a snob.

Ecomonics


Date: 7/16/2007 6:14:32 AM
Author: Serg

But of course if you will increase pavilion angle you usually can increase yield. ( Sometimes you should decrease pavilion to increase yield due flat rough, inclusions, big tilt)
That is what I am saying and this motivates financial decisions. If that has changed – or if the world has stopped spinning - please let me (and DeBeers!) know.

Color Entrapment

My whole entrance into this conversation was about the 41 degree angle as the start of color entrapment.

Sometime when I was sleeping it became about Michael’s specific 41.0/34.0 combination and even about a specific purchase here on Pricescope. Don't you guys think that once this thread became about someone’s personal stone the discussion about 41, Morse and Cowing should have been moved elsewhere?


Date: 7/15/2007 4:19:02 AM
Author: Serg

Brain,
see several images with Histogram of length ray in diamond . ( Scale from dark -zero length, white is near 7 diameters, blue is 10 diameters

First image is fro P40.75 Cr 35.50/
Avarage path is 1.335 Diameter. For other images see name of files. My respect to your grandfather
Sergey, thanks for paying respect to him. It’s remarkable that the masters from 80 years ago understood the subtle effects of color entrapment before we had the technology to confirm that. I wonder why, in my discussions with GIA, this whole issue was completely circumvented!?

In fact Michael, in all your research, why do you not tackle this issue?! Especially as we go over 41 degrees do you think those stones that trap color deserve the EX cut grade? Should potential configurations at least be analyzed for face-up color appearance?

Theory and reality


Date: 7/16/2007 7:49:20 AM
Author: Serg

Real game is much more complex. It is not for PS, Sorry
I have beat that drum quite often. Planning and polishing of diamonds is more complex than modeling it in DiamCalc (which I love to do). With respect to the theorists we should not oversimplify the planning, cutting and polishing of diamonds - as easy as DiamCalc makes it. I’m sure other manufacturers will agree. Serg Thank you for bringing this to the forefront.
 
Date: 7/16/2007 1:47:40 PM
Author: BrianTheCutter
Wow guys. I go away for 6 pages and look what happens?

Picasso

I apologize my drawings are not going to make it to The Louvre or Metropolitan Museum of Art. :) I’ll leave it to the scientists to do graphic models. My intent at the start of the thread was to show in a simple way how cutting deep increases yield. Now that other professionals are here I welcome your improved graphics. I’m used to being spoiled in South Africa with a greater consistency of more regular sawable models, unlike the rest of the world having to deal with more difficult mixes, hence my simple octahedral illustration. Sorry guys - like I said I’m a snob.

*Brian, I hope you didnt take the little fun we had with your drawings to seriously..., it was not meant towards criticism!!!
I am happy to hear you are being spoiled in SA..., most manufacturers would wish for this luxury!
As I would be surprised if you were cutting rounds out of sharp crystals...



Ecomonics



Date: 7/16/2007 6:14:32 AM
Author: Serg

But of course if you will increase pavilion angle you usually can increase yield. ( Sometimes you should decrease pavilion to increase yield due flat rough, inclusions, big tilt)
That is what I am saying and this motivates financial decisions. If that has changed – or if the world has stopped spinning - please let me (and DeBeers!) know.

*It certainly is changing and fast!!! Even DeBeers have problems keeping with the pace of change these days!!!

Color Entrapment

My whole entrance into this conversation was about the 41 degree angle as the start of color entrapment.

Sometime when I was sleeping it became about Michael’s specific 41.0/34.0 combination and even about a specific purchase here on Pricescope. Don''t you guys think that once this thread became about someone’s personal stone the discussion about 41, Morse and Cowing should have been moved elsewhere?

*Unfortunately I have been witnessing to much financial politics here on PS..., and I am sorry for this!!!



Date: 7/15/2007 4:19:02 AM
Author: Serg

Brain,
see several images with Histogram of length ray in diamond . ( Scale from dark -zero length, white is near 7 diameters, blue is 10 diameters

First image is fro P40.75 Cr 35.50/
Avarage path is 1.335 Diameter. For other images see name of files. My respect to your grandfather
Sergey, thanks for paying respect to him. It’s remarkable that the masters from 80 years ago understood the subtle effects of color entrapment before we had the technology to confirm that. I wonder why, in my discussions with GIA, this whole issue was completely circumvented!?

*Yes, I was always amazed of the "old world" Diamantaires... and the wisdom they possessed, achieved through trial and error...
I was lucky myself growing up in a house with the constant chirping noise of my fathers kerfing.


In fact Michael, in all your research, why do you not tackle this issue?! Especially as we go over 41 degrees do you think those stones that trap color deserve the EX cut grade? Should potential configurations at least be analyzed for face-up color appearance?

Theory and reality



Date: 7/16/2007 7:49:20 AM
Author: Serg

Real game is much more complex. It is not for PS, Sorry
I have beat that drum quite often. Planning and polishing of diamonds is more complex than modeling it in DiamCalc (which I love to do). With respect to the theorists we should not oversimplify the planning, cutting and polishing of diamonds - as easy as DiamCalc makes it. I’m sure other manufacturers will agree. Serg Thank you for bringing this to the forefront.
*More complex???
Its a whole world that is impossible to teach through theory or even literature!!!
In my opinion..., the only way to learn this extremely risky and complex part of getting the Rough Diamond (just) ready for its first touch on the cutting/polishing wheel is through experience (good and unfortunately sometimes bad), and trial and error.
 

It needs to be said that Brian as a cutter and educator and I as a researcher and investigator are not on opposite sides of any ideological cut grade fence, if any here have gotten that impression.



Ever since I had lively discussions with him into the night and wee hours of the Russian morning in our Moscow hotel while attending the First International Diamond Cut Conference, I have known Brian to be among those cutters including others like Bill Bray and Paul Slegers on this forum that I pay tribute to in my writing. They are among the cutters I referred to in these excerpts:




“The pavilion angle is the most critical of the diamond’s parameters. Further research by the author into all seven of the parameters that define the round brilliant has validated the accomplishments and progress of the best diamond cutters from the times of Morse and Tolkowsky until today.”

“As we celebrate the cutting achievement that is the American Ideal, we need to credit the very best of the diamond cutting profession. My research, photography and writing provide testimony to their knowledge and skill. I hold in high regard those diamond cutters from the American innovator, Henry Morse (the first to cut to ideal pavilion and crown angles) in the 1860's through to today's American Ideal cutters, who have advanced this crowning achievement in diamond cutting.

Michael Cowing, MS, FGA, A.S.G.”

PS Please don't take umbrage at my calling the optically symmetric Ideal an American Ideal, as the Belgian, Tolkowsky had much to do with its advancement, and the Japanese get credit for first promoting Hearts and Arrows optical symmetry. It is just that the American, Henry Morse, started the Ideal ball rolling, and it has become known as the American Ideal because of its adoption and promotion in the US by GIA and AGS among others.
 

RE: In fact Michael, in all your research, why do you not tackle this issue?! Especially as we go over 41 degrees do you think those stones that trap color deserve the EX cut grade? Should potential configurations at least be analyzed for face-up color appearance?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Brian,
The future evolution of my cut scoring system will easily address the variations in make that you and I know need to be made to make various colors more saleable.


Bill Bray
Diamond Cutter
 
Alright I just got done reading through all 9 pages.

I found a stone locally at a B&M store. Here are the specs.

it is a AGS Ideal 0. Color H Cut VS2. 2.31 carat

Table 61.6 depth 56 It has a crown and pavaillin angle of 41 and 35.


HCA rates a 2.2.

What do you guys think about this combo? I requested a Sarin report and should receive that tommorow.

I am very close to buying a ring. I have 2 questions.

1. I looked at some of the vendors on PS. They have a comparable stone. What to do? I am confused

2. How do I get a Diam Calc image made?

Thanks

This post has me scared/confused/worried about this combo.''

 
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