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 Post subject: Re: Heat treatment
PostPosted: Mon Mar 08, 2021 3:40 pm 
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deanins wrote:
They are pretty dark and seem to have a bluish modifier that I would like to remove.


Are we talking rough or cut gems?

Steve posted this link in another thread I found a very good read.
https://www.gia.edu/gems-gemology/summer-2019-madagascar-sapphire-heat-treatment-experiments

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 Post subject: Re: Heat treatment
PostPosted: Wed Mar 10, 2021 11:29 pm 
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This is rough with no rutile. I was going to purchase the burn out oven Steve had suggested.

It has a maximum temp of 1300* C. and I have some old info that 1100* C will clear out the blue but don't know the ramp up or down or hold times or any real particulars and not even sure if this is correct.

Thanks for any help.

Randy


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 Post subject: Re: Heat treatment
PostPosted: Thu Mar 11, 2021 3:53 pm 
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deanins wrote:
I have some Songea Sapphires that I wanted to heat treat and wondererd if anyone had any ideas on the temperatures or ramp up or ramp down times needed. Thanks any help you can give.

Randy


When I think of Songea, I think of the orange padparadscha like stones which started as pink material. Is that what you have Randy?
And later the orangish red sapphires from Songea. I really liked that stuff.


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 Post subject: Re: Heat treatment
PostPosted: Thu Mar 11, 2021 7:46 pm 
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Hi Barbra,

Some of it is pinkish, reddish, or purplish but if not heated it has a blue component that darkens the stone so it becomes a dark dark red or pink when cut. I have heated a few of these years ago and that removed the blue and they are very nice when cut.

None that I have are the orange Pad color but I know the Beryllium Diffusion treatment on these Songeas creates some amazing Pad colored stones from the Pinks.

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 Post subject: Re: Heat treatment
PostPosted: Sat Mar 13, 2021 3:01 am 
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Here is a link to recent and detailed open-access paper on the heat treatment of amethyst, to add to the knowledge base of this thread.
https://www.nature.com/articles/s41598-020-71786-1


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 Post subject: Re: Heat treatment
PostPosted: Thu Mar 18, 2021 2:12 am 
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Curiosity question...why the heating post cut instead of pre cut?

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 Post subject: Re: Heat treatment
PostPosted: Thu Mar 18, 2021 1:04 pm 
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It is not a necessary requirement. Your usually treating a cut stone for enhancement, whether it be color or some other desire. My experience is that any inclusion put under heat stress is a potential time bomb. My heating experience is very limited.

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 Post subject: Re: Heat treatment
PostPosted: Thu Mar 18, 2021 8:18 pm 
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glhays wrote:
My heating experience is very limited.


My heating experience is zip/nada...do hot flushes count? :twisted:

Seriously though, I'd be of the mind to do the heating before the hours of cutting. I'd rather the stone let go prior and if it did, there's still a good chance of cutting something and the colour has already been changed. Then there's not as much of a gamble when cutting the stone...IMO...mind you after all these years I'm starting over again and way back then, these guys were miles ahead in experience with cutting...which now puts me into the eating their dust scenario and saying 'what was that' as everyone zoomed by and the hair wafted ...models, eat your heart out...who needs a fan....

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