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 Post subject: Presidium Refractive Index Meter Ii Is it better than tradit
PostPosted: Sat Dec 01, 2012 10:41 pm 
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Hi All,

I'm new to the forums as you can probably tell. Being interested in gems/rocks for as long as I can remember, I decided to jump into gemology. After doing much research and purchasing some equipment, I find myself struggling to identify gemstones. One such piece is the Presidium Refractive Index Meter Ii, as it didnt require chemical, and from my limited experience seemed better, maybe more accurate, than the traditional ones you look through.

http://www.amazon.com/gp/product/B0083B ... 02_s00_i00

Sorry for the song and dance, I'm getting to the point now. Is this better than the traditional RI testers? Should I be worried about the accuracy of this machine?

As a side note, I did try searching through the forums for any information on this device, but didnt find any solid answers.


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 Post subject: Re: Presidium Refractive Index Meter Ii Is it better than tr
PostPosted: Sun Dec 02, 2012 2:33 pm 
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If you are new to gemology, Don't buy such an instrument. Take my word for it. :D


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 Post subject: Re: Presidium Refractive Index Meter Ii Is it better than tr
PostPosted: Sun Dec 02, 2012 2:41 pm 
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Thanks for the reply Bill, but a further explanation of why would be helpful. Is it just this specific device? RI machines in general?


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 Post subject: Re: Presidium Refractive Index Meter Ii Is it better than tr
PostPosted: Sun Dec 02, 2012 2:43 pm 
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By the way, I should mention I already purchased it and have been using it.


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 Post subject: Re: Presidium Refractive Index Meter Ii Is it better than tr
PostPosted: Sun Dec 02, 2012 3:37 pm 
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There are several threads on our board reviewing gemological instruments.
You may wish to review the following:
viewtopic.php?f=11&t=14336
viewtopic.php?f=11&t=12951
viewtopic.php?f=11&t=14515

One can simply do a search on the left and find countless posts on the subject.


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 Post subject: Re: Presidium Refractive Index Meter Ii Is it better than tr
PostPosted: Sun Dec 02, 2012 4:12 pm 
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Thanks for the direction Barbra, I was looking for my model name (presidium and presidium refractive index meter) rather than "digital refractometer". Anyone new to a subject has trouble finding answers to specific questions, as they dont know exactly what to search for. Whereas someone more knowledgeable on the subject knows exactly what to search for. I feel the need to point that out, as with most forums you get the typical derogatory statements and people thinking you were to lazy to look, but that was indeed not the case.

Now to sum up (with your help) what I've found. In case someone else wanders across this thread looking for similar answers.

Cons
All digital refractometers measure reflectivity, which is not the same as refractivity.
You are able to get the correct RI reading, only if the stone has a good polish.
You cannot measure birefringence with a digital refractometer.

Pros
The digital refractometer can aid you in finding high RI stones above 1.8.
It can aid in confirming RI.


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 Post subject: Re: Presidium Refractive Index Meter Ii Is it better than tr
PostPosted: Sun Dec 02, 2012 5:03 pm 
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Quote:
If you are new to gemology, Don't buy such an instrument. Take my word for it.


This comment, comes from someone who has likely sold more of these kind of instruments, than anybody else on the planet. So you definitely CAN take his word for it.

In researching potential improvements to this kind of instrument I have had most of the ones widely sold open and examined them and tried them out. The Presidium instrument is well made and is as good as most of them. If you did not buy it with the calibration stone set , that might not be a bad investment.
If you don't have a jeweler's refractometer then you should return it and get one of those which are more accurate and much more useful.


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 Post subject: Re: Presidium Refractive Index Meter Ii Is it better than tr
PostPosted: Sun Dec 02, 2012 5:15 pm 
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There aren't that many "over the limit" identifications you will encounter which can not be accomplished with other instruments or techniques.
Is there still time to return the reflectometer, Kanus?
(LOL....Gene and I are on the same page here. )


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 Post subject: Re: Presidium Refractive Index Meter Ii Is it better than tr
PostPosted: Sun Dec 02, 2012 6:01 pm 
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Thankfully there is! Really glad I found this forum and participating members. Just this tidbit of information has been very helpful.

Thank you!


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