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 Post subject: Annealing versus HPHT
PostPosted: Mon Nov 08, 2021 8:21 am 
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Hi, everybody.
Please, are there any difference between annealing and HPHT treatments in gemological context? Which are them, eventually?
Many thanks,
Marco


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 Post subject: Re: Annealing versus HPHT
PostPosted: Mon Nov 08, 2021 4:44 pm 
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To my awareness, annealing is a term used for metal working, whereas HPHT is used gemologically in reference to diamond treatment.


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 Post subject: Re: Annealing versus HPHT
PostPosted: Mon Nov 08, 2021 5:10 pm 
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Annealing is indeed used in metal working, but actually applies to any material heated and then slowly cooled. The only gem-related thing I know of is annealing Verneuil process ruby to relieve stress, but it's more common to split the boule to accomplish that.


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 Post subject: Re: Annealing versus HPHT
PostPosted: Tue Nov 09, 2021 3:28 am 
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Those are some results of searching for annealing @gia.edu


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 Post subject: Re: Annealing versus HPHT
PostPosted: Tue Nov 09, 2021 2:48 pm 
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Excellent research, marcop.
I still think there is a difference between HPHT and annealing.
Skimming some of the articles, it seems that annealing is often referred to as LPHT.

Someone (hint hint) should call the GIA library and ask for their precise definition of both.


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 Post subject: Re: Annealing versus HPHT
PostPosted: Tue Nov 09, 2021 3:18 pm 
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Barbra Voltaire, FGG wrote:
Someone (hint hint) should call the GIA library and ask for their precise definition of both.

:D !!!


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 Post subject: Re: Annealing versus HPHT
PostPosted: Tue Nov 09, 2021 3:39 pm 
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Isn't annealing just a process? If it is Gem or a metal, heat treatment to a specific tempature then to allow cooling at slow rate wether controlled rate or not. With metal it is common that it will be quenched in water not annealed. We all know what is most likely to happen if that were done with most gems.
So good question whether annealing should be appropriate for gemstone heat treatment.
I second the (hint, hint).
I believe there is a difference between the terms HPHT and Annealing.

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 Post subject: Re: Annealing versus HPHT
PostPosted: Sun Jan 23, 2022 11:24 pm 
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I'm a bit late for answering, but in regard of diamond treatments, annealing is a term used to refer to heat treatment subsequent to irradiation treatment, with the purpose of modifying the blue or green color that was initially obtained by irradiation.

It is not the same than HPHT treatment (which may also be refered to as HPHT annealing).


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