AGTA TUCSON GEM AND MINERAL SHOW: FEBRUARY 4-9 2020
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 Post subject: Re: Emerald Grading
PostPosted: Tue Sep 22, 2015 6:45 am 
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@raygem
what is the origin of the emeralds you have posted?

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 Post subject: Re: Emerald Grading
PostPosted: Tue Sep 22, 2015 8:10 am 
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Hi Farshid
They are Sandawana emeralds from Zimbabwe.


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 Post subject: Re: Emerald Grading
PostPosted: Wed Sep 23, 2015 3:51 am 
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Just had a thought.Wouldn't treating oiled emerald with NaOH
get the oil out?The NaOH should saponify the oil to soap which
would then wash out.


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 Post subject: Re: Emerald Grading
PostPosted: Wed Sep 23, 2015 5:19 am 
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raygem wrote:
Hi Farshid
They are Sandawana emeralds from Zimbabwe.

from its blueish green color i also thought Zim.
raygem wrote:
Just had a thought.Wouldn't treating oiled emerald with NaOH
get the oil out?The NaOH should saponify the oil to soap which
would then wash out.

effective de-oiling process is done with solvent and special equipment for pressure and heat to get the oil out of fissures and fractures. depending to oil/resin type the solvent varies. there is simply no guide for it. its more like experimental process. but for now all you can do is soaking your materials in different solvents

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 Post subject: Re: Emerald Grading
PostPosted: Sun Nov 29, 2015 12:31 pm 
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Just had a brainwave[or maybe a brainfart-I am sure you guys will let me know!!!].
I know it is dangerous to get acetone anywhere close to a naked flame,so you don't
need to warn me about this.
What I suggest is putting emeralds in acetone in a jar with a hermetic lid in a double
boiler on an electric hob i.e. no naked flame.
Heat the contents to +/- 100C,remove from double boiler and screw on the lid.
The acetone will be hot[more effective] and,as it cools down,it will create a vacuum
in the jar[more effective].This process can be repeated a few times to make sure any
oil is removed.
This process should be similar to the Soxhlet[spelling?] method to measure fat/oil in food
products,with the added advantage of the vacuum.
Admittedly,the Soxhlet method uses continuous recycling of the solvent to remove the oil,
but the principle should be the same,except for the added benefit of the vacuum.

For your added interest.if any,my surname is Priestley and Joseph Priestley is known as the
"Father of Chemistry".He discovered oxygen and Marsh Gas[but we don't talk about that much!!!].
When I was a student,I did a training job in Calne.Wiltshire and that was where he discovered
Marsh Gas in a foul-smelling pond that has a statue of him in the middle.No autographs,please!!!!!


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 Post subject: Re: Emerald Grading
PostPosted: Sat Apr 09, 2016 6:31 am 
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after heating emerald color changes?


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 Post subject: Re: Emerald Grading
PostPosted: Sat Apr 09, 2016 10:51 am 
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Hi Toptan
No colour change.If anything,the stones are brighter,
proably because they are cleaner.In any event,the
temperature would only have been around 100C and
very few[if any] gems would give a noticeable colour
change at such low temperature.
I hope I understood your question correctly.If not,do
a re-post and I will try again.


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 Post subject: Re: Emerald Grading
PostPosted: Sat Apr 09, 2016 6:34 pm 
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Heat does not affect emerald's color. It is very stable.

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