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 Post subject: How to determine RI of my refractometer fluid
PostPosted: Sat Mar 24, 2012 4:05 pm 
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Joined: Thu Sep 24, 2009 3:44 pm
Posts: 151
Location: Kingman,Az
I purchased a cheap refractometer (I know these things are considered worthless, but it was all I could afford and will upgrade to a real one later and use this one for rough.) to learn how to use and to check RI on my facet rough.

I have tested dozens of stones and am learning a lot.
I don't seem to have a problem with stones below about 1.74 but have not been able to get a reading on any of my known Garnets or anything above about 1.74.

This is the Refractometer I purchased and if you read the description this company touts how they are giving with the machine "Higher than others RI Fluid" supposedly RI 1.80.

http://www.ebay.com/itm/NEW-Gemstone-GE ... 5635197b85

OK, is there a way to test the RI of the fluid (I read in a few posts about a shadow of the fluid being able to be read, but no details as to what I am actually looking for.).

I will be purchasing a real bottle of 1.81 from Kassoy
when I can afford it, but after seeing their price I am sure the company I purchased my Refractometer from is not supplying me with a high grade fluid.

I believe knowing the RI of the fluid that I have could save me some frustrations.


Also:
I do not have any test stones to test calibration and was wondering if there are any stones that have a very specific RI that can be used.



Thanks
Harold


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 Post subject: Re: How to determine RI of my refractometer fluid
PostPosted: Sat Mar 24, 2012 4:35 pm 
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Joined: Fri Apr 17, 2009 3:53 pm
Posts: 2049
Location: Sweden
If you put a drop of liquid on the refractometer table, close the lid, turn the light on and you shall be able to see where the shadow is positioned. If 1.80 fine, if 1.74 then there might be a problem with the liquid or the refractometer scale.

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Conny Forsberg


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 Post subject: Re: How to determine RI of my refractometer fluid
PostPosted: Tue Mar 27, 2012 9:56 am 
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Joined: Sat May 21, 2011 7:09 am
Posts: 77
Location: Italy
Hi,
about the question about to determine the RI of the fluid, the answer of Conny is correct.

About "calibration stone", you will be able to calibrate the instrument for (and for only) the specific RI value of the calibration stone, not for all the scale, so I think the best way is to have some calibration stones with different RI.


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 Post subject: Re: How to determine RI of my refractometer fluid
PostPosted: Fri Apr 06, 2012 10:18 am 
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Joined: Sun Jun 28, 2009 9:56 am
Posts: 1284
For calibration, I used a clear rock crystal, and a flame fusion synthetic skyblue spinel


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