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Technical facet diagram for old mine cut?

Polyhex

Shiny_Rock
Joined
Sep 18, 2003
Messages
113
I am having a gem cutter who specializes in colored stones recut a poorly cut cushion tourmaline with an old mine design, which he has not cut before. Does anyone have a link to a lapidary facet diagram for the old mine cut which is free to share?

This is an example, but for a "Peruzzi Crown" cut rather than oldmine.

1600118958700.png

Link to diagram on facet diagrams website:
Facetdiagrams has it in "The faceter's gem cuts" by Carl M Unruh, 1977 but they do not reproduce in full due to copyright issues.
 
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monipod

Shiny_Rock
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Jun 25, 2019
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419
I can't imagine something like that being available for free to be honest, or free of copyright. Maybe your cutter can access diagrams at trade price and ask you to cover it?
 

Polyhex

Shiny_Rock
Joined
Sep 18, 2003
Messages
113
I can't imagine something like that being available for free to be honest, or free of copyright. Maybe your cutter can access diagrams at trade price and ask you to cover it?
Yes I'm totally happy to do that! There are many free lapidary diagrams but the ones I have found so far for old mine are in out of print books. Which are also buyable but take some time to arrive.

So instead of "free" I guess I mean "easily available" even for purchase.
 
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molecule

Shiny_Rock
Joined
Apr 2, 2018
Messages
232
I believe the angles would depend on the refractive index of the material, which for tourmaline would be 1.616 – 1.65.
This should fit the bill OldMineAngles.jpg
 

MollyMalone

Ideal_Rock
Premium
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Jun 2, 2013
Messages
3,164
There are a number of websites that offer faceting diagrams with instructions available free of charge e.g.,
More than 40 purported "old mine" cuts shown here:​

The problem seems to be that these sites aren't typically organized to facilitate searches for "old mine" cuts. Has your cutter tried soliciting recommendations/actual diagrams on Internet bulletin board/forums frequented by fellow lapidarists?

I'd ask the moderator to move your query to the Colored Stones forum; many of the PSers with a passion for-knowledge about colored gemstones -- both consumers & Trade members who are lapidarists -- do not frequent this Rocky Talky forum devoted to mined diamonds:
(Like @molecule, I'm thinking that you can't successfully use a faceting diagram for diamonds because tourmaline has a different refractive index.)
 

Karl_K

Super_Ideal_Rock
Trade
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Aug 4, 2008
Messages
10,342
tourmaline,,,,old mine design
Why?
It is not a great match to the material.
 

Polyhex

Shiny_Rock
Joined
Sep 18, 2003
Messages
113
I believe the angles would depend on the refractive index of the material, which for tourmaline would be 1.616 – 1.65.
Thank you!!

Edit: I am not sure if this is a real old mine design or not. The crown looks right but the pavilion looks splintery to me.
 
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Polyhex

Shiny_Rock
Joined
Sep 18, 2003
Messages
113
tourmaline,,,,old mine design
Why?
It is not a great match to the material.
Hi Karl, may I understand what you mean? 100+ years ago, colored stones were often executed in cuts similar to old cuts, and I have in my collection beautiful old mine cut stones from material with a lower RI than tourmaline.
 

Polyhex

Shiny_Rock
Joined
Sep 18, 2003
Messages
113
Has your cutter tried soliciting recommendations/actual diagrams on Internet bulletin board/forums frequented by fellow lapidarists?
Thank you, I've already gone through all the diagrams on the facet diagram site and the vast majority are "inspired by designs" and don't have much to do with the original old mine cut. The facet diagram which looks correct is in the one result referenced in the 1970s book above. I would prefer pricescope's view of an old mine cut facet diagram vs. another board's, personally, if pricescope's opinion is available. :)
 

Karl_K

Super_Ideal_Rock
Trade
Joined
Aug 4, 2008
Messages
10,342
Hi Karl, may I understand what you mean? 100+ years ago, colored stones were often executed in cuts similar to old cuts, and I have in my collection beautiful old mine cut stones from material with a lower RI than tourmaline.
Sure they were that does not mean they are optimal.
The cut doesn't do much to help color nor add a lot of life to a stone of that RI.
A cut designed for it or similar ri stones helps the color pop and adds life to the stone.
 

Polyhex

Shiny_Rock
Joined
Sep 18, 2003
Messages
113
Sure they were that does not mean they are optimal.
The cut doesn't do much to help color nor add a lot of life to a stone of that RI.
A cut designed for it or similar ri stones helps the color pop and adds life to the stone.
Let me explain more -- The stone is in a badly windowed mixed cut with a brilliant crown and step cut pavilion. Because of the cushion brilliant shape, the crown already resembles an old mine. His fix for the window will be to recut the pavilion as brilliant, and my request for him is to leverage the old mine brilliant design with broad facets. He will adapt the design to save weight, for the optics of the material, and to match the crown better.
 
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