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 Post subject: Re: Red/Pink Tourmaline heat treatment
PostPosted: Thu Jul 25, 2013 8:49 pm 
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One of the major things that first attracted me to gemcutting was the charm of a crystal taking millennia to grow, and my challenge was to reveal its intrinsic beauty.

But practically speaking, now, when I cut for fun, or to test a lap candidate, it's CZ or YAG. I have no trouble getting rid of the stones! (14 nieces).

Remember, there were people a few years ago that started a fad among local bikers where they were faceting the bases of Michelobe bottles.

But it does feel better to cut something from the ground, I think, regardless of monetary return. It's the idea of it.


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 Post subject: Re: Red/Pink Tourmaline heat treatment
PostPosted: Thu Jul 25, 2013 9:10 pm 
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There are a few man-mades that I enjoy. One in particular my dad just picked up was a faceted piece of leaded glass which was used for radiation shielding of plutonium in the manhatten project. It has a light yellow coloration from being irradiated, and with such high lead content it sparkles like crazy. That has enough nerd cred associated with it to make me not mind at all that it isn't natural.

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 Post subject: Re: Red/Pink Tourmaline heat treatment
PostPosted: Fri Jul 26, 2013 12:28 am 
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G_Madison wrote:
...Are you using an investment that matches the expantion rate of the stone or do you use a steel ring when investing the stones? sorry for the newbness,Iv'e never tryed heating material before. :oops:


You don't mix investment with water and pour it around the gem - you simply place the gem in loose investment powder to insulate it from too rapid of temperature change.

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 Post subject: Re: Red/Pink Tourmaline heat treatment
PostPosted: Fri Jul 26, 2013 10:01 am 
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What would be the reason to use a silica based very fine dry powder to immerse your rough in for heating? This stuff is not good to breath when in powder form and I always use a respirator when handling dry investment powder. What is the advantage of investment powder over fine grain sand, such as that used for sand casting, that doesn't have the health hazards associated with it?

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 Post subject: Re: Red/Pink Tourmaline heat treatment
PostPosted: Fri Jul 26, 2013 8:50 pm 
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Gearloose wrote:
But it does feel better to cut something from the ground, I think, regardless of monetary return. It's the idea of it.

It's the cutting itself, the perfection of the technique and the touch of getting there, wherever that is, wherever I want it to be, that I find most interesting. On the left, 793 cts of CZ fun! Cost: $27. On the right, 11 cts malaya garnet... Cost: $71.50.
Hey, maybe when I get my Masters cert, I'll think about the one on the right. Until then-
Ya, girls just wanna have fun!!! Lots and lots of fun :)
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 Post subject: Re: Red/Pink Tourmaline heat treatment
PostPosted: Fri Jul 26, 2013 9:04 pm 
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"You don't mix investment with water and pour it around the gem - you simply place the gem in loose investment powder to insulate it from too rapid of temperature change."

I was under the impression that a solid mass is more stable with a solid mass encasing it.as in investment and liner with a ring.would this not help the stone from shattering?it may crack,but the stone would not be a total loss in my opinion.just wondering on this point,iv'e never tryed it before.the water in the investment allso evaporates if im correct.



"What would be the reason to use a silica based very fine dry powder to immerse your rough in for heating? This stuff is not good to breath when in powder form and I always use a respirator when handling dry investment powder. What is the advantage of investment powder over fine grain sand, such as that used for sand casting, that doesn't have the health hazards associated with it?"

Would not the material that you cover your rough with under heat impart impuritys into your stone in the form of trace elements? Silica i believe is a nutral agent is it not?
I would love some more advice on this if you all have time as there is alot that i dont understand.

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 Post subject: Re: Red/Pink Tourmaline heat treatment
PostPosted: Sun Nov 03, 2013 2:56 am 
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Thank you very much lisa.

I went through your article. It was very interesting. It gave me hope to try with heat treating Tourmaline.

And I have a couple of dark red to violet Spinels. the origin of these stones should be Madacascar.

If you have any experience in heating such Spinels I would like to know.

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Risly
Sri Lanka


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 Post subject: Re: Red/Pink Tourmaline heat treatment
PostPosted: Sat Dec 28, 2013 5:34 pm 
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I finally had a chance to have a go at it myself! We heated 4 hunks of rough tourmaline of varying colors (too included to facet, so who cares if some inclusions propogate).
One black with yellow clarity visible on the edges, one dark, murky blue-green (open C-axis though), one murky "watermelon" with green outsides and a blue core, one dark yellow-green dichroic stone which had been previously tumbled a bit.
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We heated them to 530 c in 125 increments with an hour between rampups (and 30 minutes before the final 30 degrees) and a 2 hour soak. Then we just turned it off and let it cool for a few hours.
The results:
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The black did nothing at all (to be expected). The yellow lightened a bit and split. The blue-cored one split and the center lightened to an aquamarine-blue which provides much better contrast with the green rim. The green one was the real star; it split, and half of it turned a gorgeous apple-green of perfect tone. The splitting is generally fine on these, since I can just put a flat polish on the ends. Tourmaline slices are always popular.

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The green one was really fuzzy when I dumped it out (the white is the silica sand we used for filler inside the crucible). I dunno why that would be; I guess something really was coming out of the stone.

So, I'd call it a success thus far. We have more cooking as I type. Thanks again to Lisa for her awesome article which has inspired our efforts.

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