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 Post subject: Views on Gem Tester instruments
PostPosted: Wed Jan 29, 2014 11:21 am 
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Hi all:

Wondering what people think of instruments such as the Presidium Gem Tester, which supposedly separates many gemstones based on thermal conductivity.

It's frustrating not to be able to test small or inaccessible gems when they are set in a piece -- meaning I can't get a gem surface onto the refractometer. Often they are small or awkwardly located so it's also hard to see the inclusions clearly.

I guess this is where a gem tester would come in, but I've never used one. Love to hear thoughts on these gadgets.

Thanks,

Neil


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 Post subject: Re: Views on Gem Tester instruments
PostPosted: Wed Jan 29, 2014 11:27 am 
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Hi NeilS.
If you search our forum for reflectometers, like the Presidium, you will see that we have found them unreliable.


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 Post subject: Re: Views on Gem Tester instruments
PostPosted: Wed Jan 29, 2014 12:54 pm 
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I'll do that. Thanks. I did not know that was the technical name for them. Not surprised they are unreliable.

Neil


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 Post subject: Re: Views on Gem Tester instruments
PostPosted: Thu Jan 30, 2014 7:19 am 
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NeilS wrote:
I'll do that. Thanks. I did not know that was the technical name for them. Not surprised they are unreliable.

Neil


IMHO they are NOT unreliable, you just have to use them as they are meant to be used - As a part of identification, not as the only instrument to identify a gemstone...

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~~~Lennie~~~


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 Post subject: Re: Views on Gem Tester instruments
PostPosted: Thu Jan 30, 2014 8:44 am 
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Thanks Lennie. I have been reviewing some threads on the issue, and I picked up that at a minimum, perfect surface luster is indispensable for the instrument to work properly. That would not be any help for the task I was trying to do, which was get an ID on a tiny stone set in jewelry. The polish didn't look very good, and it was hard to access the stone with any kind of instrument. BUT -- with dedicated effort I was able to get my handheld spectrometer in the right spot, and some light behind it. And bingo, there was the signature spectrum for ruby, including a big, bright chromium transmission line. With that, and a good dichroscope reading, I was able to make a good enough call for the project in hand.

Thanks,

Neil


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