41 degree pavilion angle footnote

[elmo]

While revisiting some of the rambling discussions about mind-cleanness and 41-degree pavilion angles, I ran across this which I thought was interesting. One of the major manufacturers of really nice super-ideal rounds, which often cuts pavilions to 41 degrees, includes this diagram with each stone sold under the brand. It states that the "optimal" pavilion angle is 40.7 degrees (image attached). So regardless of whether the statement is based more on science or on tradition, they're clearly implying that 41 degrees is acceptable but somehow sub-optimal. The fascinating original discussion involved many bona fide experts so I can't add to the knowledge base that wasn't already touched on there except this bit of irony.

 

[strmrdr]

must be old they are cutting a lot of 41/34s now days.

 

[elmo]

Yes, it''s a few months old

. This business is steeped in tradition, isn''t it.

 

[pyramid]

Interesting.

 

[Ellen]

Something must gave changed their mind, since as strm said, they do indeed cut that combo, a lot.

 

[Rhino]

Thanks for posting that Elmo. Outdated research on an old brochure that was never pulled off the web. You see acceptable angles there ranging from 40.2 to 41.2. Old AGS standards. Most current research doesn't even consider what pavilion angle is being used until they know the accompanying crown angle. To make a judgement of one without the knowledge of the other is pure speculation. There are gorgeous diamonds, equally beautiful as any H&A with 41.4 pavilion angles if it has the proper crown angle.

Also, if one were to stick to the literalness of that brochure then a 40.8 or 40.9 is sub par as well.

Peace,

 

[diagem]

Date: 10/27/2007 12:28:40 PM
Author: Rhino
Thanks for posting that Elmo. Outdated research on an old brochure that was never pulled off the web. You see acceptable angles there ranging from 40.2 to 41.2. Old AGS standards. Most current research doesn''t even consider what pavilion angle is being used until they know the accompanying crown angle. To make a judgement of one without the knowledge of the other is pure speculation. There are gorgeous diamonds, equally beautiful as any H&A with 41.4 pavilion angles if it has the proper crown angle.

Also, if one were to stick to the literalness of that brochure then a 40.8 or 40.9 is sub par as well.

Peace,

So true....., and may I add..., nicely explained!!!

That is one of the many reasons fancy shapes are almost impossible to Ideal-ize

All facet sizes, positions and angles of crown vs. pavilion must complement one another while taking shape (outline) into consideration!!!

 

[gontama]

It is actually not surprising to me. LK also says something similar, but they do cut 41P (at least some of them). Have seen only a few of them in person but one of them is a very well cut one and did blow away another famous brand in front of my wife''s eye. They may feel easy to say something that sounds familiar to the vast majority of the audience.

 

[Rhino]

Date: 10/27/2007 11:13:38 AM
Author: Ellen
Something must gave changed their mind, since as strm said, they do indeed cut that combo, a lot.

Ellen that smiley above cracked me up.

Thanks Diagem. So so true about the fancies too. The more I look at and compare to other tecky results the more I learn how not reliable some are for communicating diamond beauty.

Interesting gontama. In the near future a book is being released by a fellow research gemologist (Mr. Al Gilbertson G.G.) who has researched ideal cuts and their history perhaps more than anyone here. He has quite a bit to say about the 41.0 degree pavilion angle, which when I talked with him about it had some very enlightening things to say. I haven't read any portions of his book yet but he has a strong opinion on the subject, which after my own lab testing and observations can't help but agree with.

An interesting preview dispelling some already perceived myths about ideal cut diamonds are commented by Al Glibertson himself at this link.

You'll see two links saying "American Cut". The first is audio the 2nd is video. Henry Morse whom he mentions in this interview made what is perhaps the most remarkable discovery of his time and all revolving around the 41.0 degree pavilion angle 35 crown combo. To my knowledge, in those days the means to cut diamonds precisely to 40.7 or 40.8 etc. were non existent.

 

[JohnQuixote]

 

[Rhino]

Well said John.

I think it should be emphasized/clarified that to say that any one angle (no matter what it is) is sub par without knowing it''s corellating crown angle is misleading.

For example if I come here and suggest that a pavilion angle of 41.2 is sub par in and of itself would be a misleading statement. Why? Because there is no knowledge of it''s corresponding crown angle.

If I qualify this and say 41.2 with a 35.8 crown is a sub par combo I would be accurate, however if I state that 41.2 with a 33.5 crown is in some way a 2nd rate diamond this would be misleading. Does this make sense to you?

Kind Regards,

 

[JohnQuixote]

Date: 10/27/2007 5:34:24 PM
Author: Rhino
Well said John.

I think it should be emphasized/clarified that to say that any one angle (no matter what it is) is sub par without knowing it's corellating crown angle is misleading.

For example if I come here and suggest that a pavilion angle of 41.2 is sub par in and of itself would be a misleading statement. Why? Because there is no knowledge of it's corresponding crown angle.

If I qualify this and say 41.2 with a 35.8 crown is a sub par combo I would be accurate, however if I state that 41.2 with a 33.5 crown is in some way a 2nd rate diamond this would be misleading. Does this make sense to you?

Kind Regards,

It does. And if we're talking about a stone selected by you I trust it would not be second rate. If it were on a list or from an unknown source I'd want more info: Poor optical symmetry and angle variance can make such configurations wobbly, but a diamond with such issues would be rejected by you, our company and other cut-focused sellers.

 

[Ellen]

Date: 10/27/2007 5:08:11 PM
Author: Rhino

Date: 10/27/2007 11:13:38 AM
Author: Ellen
Something must gave changed their mind, since as strm said, they do indeed cut that combo, a lot.

Ellen that smiley above cracked me up.

Good!

And that should be have, not gave.

I really miss unlimited editing....


Great thread/info.

 

[Garry H (Cut Nut)]

Date: 10/27/2007 1:14:05 PM
Author: DiaGem

Date: 10/27/2007 12:28:40 PM
Author: Rhino
Thanks for posting that Elmo. Outdated research on an old brochure that was never pulled off the web. You see acceptable angles there ranging from 40.2 to 41.2. Old AGS standards. Not so - these are not old AGS proportions - but they are obviously some in house ojd proportions Most current research doesn''t even consider what pavilion angle is being used until they know the accompanying crown angle. To make a judgement of one without the knowledge of the other is pure speculation. There are gorgeous diamonds, equally beautiful as any H&A with 41.4 pavilion angles if it has the proper crown angle.

Also, if one were to stick to the literalness of that brochure then a 40.8 or 40.9 is sub par as well.

Peace,

So true....., and may I add..., nicely explained!!!

That is one of the many reasons fancy shapes are almost impossible to Ideal-ize Of course DG the idea that Ideal can exist is like the phlosphers search for truth. But finding OPTIMAL proportions for any cut is indeed feasable. DiamCalc Pro does make it possible and now that this tool has been released to the market we should expect to see numerous new and better cuts coming to the market.

All facet sizes, positions and angles of crown vs. pavilion must complement one another while taking shape (outline) into consideration!!!

 

[diagem]

Date: 10/27/2007 11:16:23 PM
Author: Garry H (Cut Nut)

Date: 10/27/2007 1:14:05 PM
Author: DiaGem

Date: 10/27/2007 12:28:40 PM
Author: Rhino
Thanks for posting that Elmo. Outdated research on an old brochure that was never pulled off the web. You see acceptable angles there ranging from 40.2 to 41.2. Old AGS standards. Not so - these are not old AGS proportions - but they are obviously some in house ojd proportions Most current research doesn''t even consider what pavilion angle is being used until they know the accompanying crown angle. To make a judgement of one without the knowledge of the other is pure speculation. There are gorgeous diamonds, equally beautiful as any H&A with 41.4 pavilion angles if it has the proper crown angle.

Also, if one were to stick to the literalness of that brochure then a 40.8 or 40.9 is sub par as well.

Peace,

So true....., and may I add..., nicely explained!!!

That is one of the many reasons fancy shapes are almost impossible to Ideal-ize Of course DG the idea that Ideal can exist is like the phlosphers search for truth. But finding OPTIMAL proportions for any cut is indeed feasable. DiamCalc Pro does make it possible and now that this tool has been released to the market we should expect to see numerous new and better cuts coming to the market.

All facet sizes, positions and angles of crown vs. pavilion must complement one another while taking shape (outline) into consideration!!!

In regards to fancies:

Optimal proportions = beauty?
New cuts are being experimented all the time..., better cuts (in fancies) are being cut mainly in the higher quality segments..., as demand dictates it.
And if you want to survive in this "wacko" world of Diamond manufacturing..., you have got to be "good"!!! And stock the good stuff!!!

But when it comes to beauty......., "new and better" does not always mean more beautifull!!!

 

[Garry H (Cut Nut)]

Date: 10/28/2007 2:08:05 AM
Author: DiaGem

Date: 10/27/2007 11:16:23 PM
Author: Garry H (Cut Nut)

Date: 10/27/2007 1:14:05 PM
Author: DiaGem



So true....., and may I add..., nicely explained!!!

That is one of the many reasons fancy shapes are almost impossible to Ideal-ize Of course DG the idea that Ideal can exist is like the phlosphers search for truth. But finding OPTIMAL proportions for any cut is indeed feasable. DiamCalc Pro does make it possible and now that this tool has been released to the market we should expect to see numerous new and better cuts coming to the market.

All facet sizes, positions and angles of crown vs. pavilion must complement one another while taking shape (outline) into consideration!!!

In regards to fancies:

Optimal proportions = beauty?
New cuts are being experimented all the time..., better cuts (in fancies) are being cut mainly in the higher quality segments..., as demand dictates it.
And if you want to survive in this ''wacko'' world of Diamond manufacturing..., you have got to be ''good''!!! And stock the good stuff!!!

But when it comes to beauty......., ''new and better'' does not always mean more beautifull!!!

optimal proportions are those that optimize a diamonds beauty, saleability and the yeild from the rough diamond.

 

[diagem]

Date: 10/28/2007 3:40:36 AM
Author: Garry H (Cut Nut)

Date: 10/28/2007 2:08:05 AM
Author: DiaGem

Date: 10/27/2007 11:16:23 PM
Author: Garry H (Cut Nut)

Date: 10/27/2007 1:14:05 PM
Author: DiaGem



So true....., and may I add..., nicely explained!!!

That is one of the many reasons fancy shapes are almost impossible to Ideal-ize Of course DG the idea that Ideal can exist is like the phlosphers search for truth. But finding OPTIMAL proportions for any cut is indeed feasable. DiamCalc Pro does make it possible and now that this tool has been released to the market we should expect to see numerous new and better cuts coming to the market.

All facet sizes, positions and angles of crown vs. pavilion must complement one another while taking shape (outline) into consideration!!!

In regards to fancies:

Optimal proportions = beauty?
New cuts are being experimented all the time..., better cuts (in fancies) are being cut mainly in the higher quality segments..., as demand dictates it.
And if you want to survive in this ''wacko'' world of Diamond manufacturing..., you have got to be ''good''!!! And stock the good stuff!!!

But when it comes to beauty......., ''new and better'' does not always mean more beautifull!!!

optimal proportions are those that optimize a diamonds beauty, saleability and the yeild from the rough diamond.

In my opinion, beauty is separated in the equation from saleability and Yield!!!
That''s why I think optimizing Fancy Shape cuts is a whole different world from RB''s...

 

[Garry H (Cut Nut)]

Date: 10/28/2007 4:27:02 AM
Author: DiaGem

Date: 10/28/2007 3:40:36 AM
Author: Garry H (Cut Nut)

optimal proportions are those that optimize a diamonds beauty, saleability and the yeild from the rough diamond.

In my opinion, beauty is separated in the equation from saleability and Yield!!!
That''s why I think optimizing Fancy Shape cuts is a whole different world from RB''s...

We offer all three for no extra charge DG.
Win for consumers
win for dealers
win for cutters

 

[diagem]

Date: 10/28/2007 5:25:06 AM
Author: Garry H (Cut Nut)

Date: 10/28/2007 4:27:02 AM
Author: DiaGem

Date: 10/28/2007 3:40:36 AM
Author: Garry H (Cut Nut)

optimal proportions are those that optimize a diamonds beauty, saleability and the yeild from the rough diamond.

In my opinion, beauty is separated in the equation from saleability and Yield!!!
That''s why I think optimizing Fancy Shape cuts is a whole different world from RB''s...

We offer all three for no extra charge DG.
Win for consumers
win for dealers
win for cutters

And win for you...

And when we will have a chance to meet..., I would be more than interested to view and hear more...

But..., that is still besides my point..., which is you cant optimize beauty..., especialy in Fancy shaped Diamonds!

 

[Garry H (Cut Nut)]

HK fair in Feb/March?
Vegas in june?

I made this small example of a cushion in a few minutes DG.
I can only show you about 20th of the image because of the 100kb limit for images.

in this example I ran crown height and pavilion depth %, but I can vary every one of the parameters for each facet - about 24 variables in total.
I would run this chart and find the best ranges (there are more than 1 - which is how we can get various best yeilds for different shaped pieces of rough).
Then I would work on various minor facets. All up this would be at least 1 weeks work.

And then we simply add the various plans into the Helium Rough scanner and the highest value option will automatically come up for each piece of rough. Some dealers will reject some plans because they have certain rules (like Harry Winston - I have seen their selection criteria for cushion shapes).

Of course i would also run several other types of images - make sure there are no nasty fish eyes etc and look at crushed glass vs bright sparkly cushions or whatever the dealer / client pays most for.

And that is before we consider the ETAS data for brilliance fire and scintillation (actually about 20 diferent data sets with variables for pupil size and single eye or stereo.


So, the short answer is YES, we can make a 3 win OPTIMIZED cut for any shape, new or old.
(it would take you years and several million dollars of rough to do this the old way)

BTW DG, I think there is someone near you who is using this software as the basis of a consultancy.

 

[diagem]

Date: 10/28/2007 7:10:52 AM
Author: Garry H (Cut Nut)
HK fair in Feb/March?
Vegas in june?

I made this small example of a cushion in a few minutes DG.
I can only show you about 20th of the image because of the 100kb limit for images.

in this example I ran crown height and pavilion depth %, but I can vary every one of the parameters for each facet - about 24 variables in total.
I would run this chart and find the best ranges (there are more than 1 - which is how we can get various best yeilds for different shaped pieces of rough).
Then I would work on various minor facets. All up this would be at least 1 weeks work.

And then we simply add the various plans into the Helium Rough scanner and the highest value option will automatically come up for each piece of rough. Some dealers will reject some plans because they have certain rules (like Harry Winston - I have seen their selection criteria for cushion shapes).

You are talking about "highest value option"??? In regards to polished yield..., correct? The rest of the value is based on rarity?

Of course i would also run several other types of images - make sure there are no nasty fish eyes etc and look at crushed glass vs bright sparkly cushions or whatever the dealer / client pays most for.

Works on all types of appearances? from brilliant to crushed ice to all other tons of modifiers?? Any modified shape?

And that is before we consider the ETAS data for brilliance fire and scintillation (actually about 20 diferent data sets with variables for pupil size and single eye or stereo.


So, the short answer is YES, we can make a 3 win OPTIMIZED cut for any shape, new or old.
(it would take you years and several million dollars of rough to do this the old way)

If I needed it..., you are probably right..., but again..., as far as beauty or as you call it (client requirements), when I study any type of rough Diamond model..., I would probably be in better position to know the appearance and yield "I" would need to cut out of that specific Rough!
But what you are showing would be great for manufacturers wanting to produce consistently!!!

BTW DG, I think there is someone near you who is using this software as the basis of a consultancy.

Speaking of cushions..., I have yet seen any manufacturers (except two "huge" Co.''s one from Antwerp and one from Russia) succeeding to keep their cushion production in consistancy!!!

 

[Garry H (Cut Nut)]

Date: 10/28/2007 7:58:48 AM
Author: DiaGem

Date: 10/28/2007 7:10:52 AM
Author: Garry H (Cut Nut)
HK fair in Feb/March?
Vegas in june?

I made this small example of a cushion in a few minutes DG.
I can only show you about 20th of the image because of the 100kb limit for images.

in this example I ran crown height and pavilion depth %, but I can vary every one of the parameters for each facet - about 24 variables in total.
I would run this chart and find the best ranges (there are more than 1 - which is how we can get various best yeilds for different shaped pieces of rough).
Then I would work on various minor facets. All up this would be at least 1 weeks work.

And then we simply add the various plans into the Helium Rough scanner and the highest value option will automatically come up for each piece of rough. Some dealers will reject some plans because they have certain rules (like Harry Winston - I have seen their selection criteria for cushion shapes).

You are talking about ''highest value option''??? In regards to polished yield..., correct? The rest of the value is based on rarity? remeber value is weight times price and price is a function of demand / quality as well as rarity

Of course i would also run several other types of images - make sure there are no nasty fish eyes etc and look at crushed glass vs bright sparkly cushions or whatever the dealer / client pays most for.

Works on all types of appearances? from brilliant to crushed ice to all other tons of modifiers?? Any modified shape? You can use this software for any shape, existing, or use the built in cut designer to make models with variable minor facets (another worlds first)

And that is before we consider the ETAS data for brilliance fire and scintillation (actually about 20 diferent data sets with variables for pupil size and single eye or stereo.


So, the short answer is YES, we can make a 3 win OPTIMIZED cut for any shape, new or old.
(it would take you years and several million dollars of rough to do this the old way)

If I needed it..., you are probably right..., but again..., as far as beauty or as you call it (client requirements), when I study any type of rough Diamond model..., I would probably be in better position to know the appearance and yield ''I'' would need to cut out of that specific Rough!
But what you are showing would be great for manufacturers wanting to produce consistently!!! yes

BTW DG, I think there is someone near you who is using this software as the basis of a consultancy.

Speaking of cushions..., I have yet seen any manufacturers (except two ''huge'' Co.''s one from Antwerp and one from Russia) succeeding to keep their cushion production in consistancy!!! if a company has a specific ''look'' they want to replicate we can broaden their range of proportions that produce such looks

 

[diagem]

Date: 10/28/2007 7:10:52 AM
Author: Garry H (Cut Nut)
HK fair in Feb/March?
Vegas in june?

What??? No Basel 08?

 

[Garry H (Cut Nut)]

Date: 10/28/2007 5:15:19 PM
Author: DiaGem

Date: 10/28/2007 7:10:52 AM
Author: Garry H (Cut Nut)
HK fair in Feb/March?
Vegas in june?

What??? No Basel 08?

50/50 chance

 

[diagem]

Date: 10/28/2007 6:38:24 PM
Author: Garry H (Cut Nut)

Date: 10/28/2007 5:15:19 PM
Author: DiaGem

Date: 10/28/2007 7:10:52 AM
Author: Garry H (Cut Nut)
HK fair in Feb/March?
Vegas in june?

What??? No Basel 08?

50/50 chance

It will be a pleasure if you make it....