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 Post subject: Colored diamonds?
PostPosted: Sun Nov 20, 2016 10:15 pm 
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Questions for the diamond cutters:

Do you often get a chance to cut diamonds that are pink, blue, etc.? If so, is there a different approach than that used to cut white/ colorless diamonds? From what I understand about diamond cutting, you don't use any kind of protractor type of device but instead estimate various angles and facet placement by eye. Is it the same when you cut colored diamonds? Does it present the same level of difficulty or skill? Which do you prefer, both aesthetically and to cut?


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 Post subject: Re: Colored diamonds?
PostPosted: Mon Nov 21, 2016 10:56 am 
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The chance to cut coloured diamonds (particularly pink diamonds) will come to the ordinary hobbyist very rarely, they are just too expensive. Diamond cutting tends to fall into two categories, ordinary smalish stones, which are usually cut by computer controlled machines, and top end stones which are cut by hand. The consideration is that the hand cutter has such a wealth of knowledge and experience that protractors and measures are unnecessary. If you ever get the chance to visit Asschers in Amsterdam, and can organise a visit to watch their cutters at work (they organise visits from time to time), do not hesitate.


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 Post subject: Re: Colored diamonds?
PostPosted: Mon Nov 21, 2016 11:03 am 
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Alan F. wrote:
The chance to cut coloured diamonds (particularly pink diamonds) will come to the ordinary hobbyist very rarely, they are just too expensive. Diamond cutting tends to fall into two categories, ordinary smalish stones, which are usually cut by computer controlled machines, and top end stones which are cut by hand. The consideration is that the hand cutter has such a wealth of knowledge and experience that protractors and measures are unnecessary. If you ever get the chance to visit Asschers in Amsterdam, and can organise a visit to watch their cutters at work (they organise visits from time to time), do not hesitate.


Oh, I would love to see that! Loving diamonds is sort of a guilty pleasure for me, since i can only cut colored stones....makes me feel like a traitor, lol. I love both colorless and naturally colored diamonds. I would guess that there isn't much of a difference between cutting either or, but it pays to ask and not assume. I know next to nothing on the subject of colored diamonds, and have no idea if there is such a thing as color zoning issues when cutting them. Guess I should look it up rather than give in to the temptation of asking someone here to go through the effort to explain it to me.


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 Post subject: Re: Colored diamonds?
PostPosted: Mon Nov 21, 2016 3:22 pm 
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Tygurrr-I wrote:
Questions for the diamond cutters:

Do you often get a chance to cut diamonds that are pink, blue, etc.? If so, is there a different approach than that used to cut white/ colorless diamonds? From what I understand about diamond cutting, you don't use any kind of protractor type of device but instead estimate various angles and facet placement by eye. Is it the same when you cut colored diamonds? Does it present the same level of difficulty or skill? Which do you prefer, both aesthetically and to cut?


Fancy yellow are the colored diamonds that I have cut most often.
I prefer higher crown angles and smaller tables for colored diamonds. 33-35 degree main angles and table diameters of 53-58%.
Cutters always use tangs with protractor angle adjustments for cross-working. That is an operation that should never be done solely by eye. It is possible to brillianteer star facets onto the crown by eye, but I would not recommend brillianteering the top and bottom halves by eye. The bottom half angles affect light return and scintillation to a great degree.
I like cutting colored diamonds and would always welcome more.

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 Post subject: Re: Colored diamonds?
PostPosted: Mon Nov 21, 2016 8:53 pm 
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thomas.adamas wrote:
Tygurrr-I wrote:
Questions for the diamond cutters:

Do you often get a chance to cut diamonds that are pink, blue, etc.? If so, is there a different approach than that used to cut white/ colorless diamonds? From what I understand about diamond cutting, you don't use any kind of protractor type of device but instead estimate various angles and facet placement by eye. Is it the same when you cut colored diamonds? Does it present the same level of difficulty or skill? Which do you prefer, both aesthetically and to cut?


Fancy yellow are the colored diamonds that I have cut most often.
I prefer higher crown angles and smaller tables for colored diamonds. 33-35 degree main angles and table diameters of 53-58%.
Cutters always use tangs with protractor angle adjustments for cross-working. That is an operation that should never be done solely by eye. It is possible to brillianteer star facets onto the crown by eye, but I would not recommend brillianteering the top and bottom halves by eye. The bottom half angles affect light return and scintillation to a great degree.
I like cutting colored diamonds and would always welcome more.


Very interesting, do you adjust the crown angles and table to intensify the color? Just goes to show, it *does* pay to ask, and not just assume. I have read a little about diamond cutting, but never knew that diamond cutters also use a modified protractor.

At any rate, they are very beautiful, and I don't blame you for wanting to cut more: may you be blessed with a shower of colored diamonds to cut. Ethically mined, hopefully. I read that the pink diamonds may be the most popular of the fancy colored diamonds, but I think that blue diamonds are gorgeous, too.


Last edited by Tygurrr-I on Tue Nov 22, 2016 6:00 pm, edited 2 times in total.

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 Post subject: Re: Colored diamonds?
PostPosted: Mon Nov 21, 2016 9:24 pm 
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Tygurrr-I wrote:
Very interesting, do you adjust the crown angles and table to intensify the color? Just goes to show, it *does* pay to ask, and not just assume. I have read a little about diamond cutting, but never knew that diamond cutters also use a modified protractor.

At any rate, they are very beautiful, and I don't blame you for wanting to cut more. I read that the pink diamonds may be the most popular of the fancy colored diamonds, but I think that blue diamonds are gorgeous, too.


A fuller crown will produce a slightly more intense color and more evident dispersion.

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 Post subject: Re: Colored diamonds?
PostPosted: Tue Nov 22, 2016 11:17 am 
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thomas.adamas wrote:
Tygurrr-I wrote:
Very interesting, do you adjust the crown angles and table to intensify the color? Just goes to show, it *does* pay to ask, and not just assume. I have read a little about diamond cutting, but never knew that diamond cutters also use a modified protractor.

At any rate, they are very beautiful, and I don't blame you for wanting to cut more. I read that the pink diamonds may be the most popular of the fancy colored diamonds, but I think that blue diamonds are gorgeous, too.


A fuller crown will produce a slightly more intense color and more evident dispersion.


If you ever have the opportunity and the mind to do so, would you consider posting a few pics to compare, say, a colored diamond you cut to a similar shaped "white" diamond? :D don't mean to put you on the spot or anything. But now you have me curious, and I wouldn't know where else to get this visual comparison. If it's a hassle, don't worry about it. Especially, of course, if this is standard practice among diamond cutters, and there is some sort of resource available to peruse.

Some of my most loved colored stones work have been famous diamond replicas, particularly the Hope diamond. I'm embarrassed to admit that I am having a senior moment ( found an entire box of cut gems that I know I faceted, but can't remember doing them), and can't recall which material I used, but I think it was either an aqua or CZ. It was beautiful, and garnered lots of praise.

Since you are both a diamond cutter and colored stone faceter, do you ever replicate famous diamonds in either material? Either for yourself or because someone requests it? Sorry for all the ?


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 Post subject: Re: Colored diamonds?
PostPosted: Tue Nov 22, 2016 6:07 pm 
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I have not replicated any famous diamonds in CZ, but I do know of a faceter in NYC who has a business doing just that.
You can use GemCAD animations to see the difference between a white diamond with a shallow crown and a colored diamond with a full crown. Choose an IR of 2.41 and dispersion of 0.044, then choose a standard round brilliant colorless, then the color of your choice.

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 Post subject: Re: Colored diamonds?
PostPosted: Tue Nov 22, 2016 7:48 pm 
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thomas.adamas wrote:
I have not replicated any famous diamonds in CZ, but I do know of a faceter in NYC who has a business doing just that.
You can use GemCAD animations to see the difference between a white diamond with a shallow crown and a colored diamond with a full crown. Choose an IR of 2.41 and dispersion of 0.044, then choose a standard round brilliant colorless, then the color of your choice.


From what I recall, it was a lot of fun to re-create diamond replicas, and I will do it again, both with CZ and some gem varieties I have lying around.

You know, it never even occurred to me to utilize GemCad the way you suggested, thank you for the suggestion.


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