Post subject: refractometer with or without RI fluid?
Posted: Fri Dec 13, 2013 10:19 am
Valued Contributor
Joined: Fri Nov 01, 2013 9:16 am Posts: 239 Location: Germany
Hi there, I´m using at the moment the presidium duo tester (which I find as one test of plenty very useful). Now as i´m digging deeper into gemmology I´d like to buy are "real" refractometer. As I saw most of them are using RI fluid, but some don´t. As I like technical gadgets I looked around to find some which i can plug into my computer. I found: Presidium Refractive Index Meter II (PRIM II)
which seems quite nice. What do you think of using this kind of Refractometer without RI fluid? are there disadvantages? Whats about birefringence or uniaxial, biaxial, are these measurements possible with the digital versions? which one would you suggest?
Post subject: Re: refractometer with or without RI fluid?
Posted: Fri Dec 13, 2013 11:15 am
Valued Contributor
Joined: Fri Nov 01, 2013 9:16 am Posts: 239 Location: Germany
ah ok, I was confused because in the product description and on google you find these gadgets, when you search for digital refractometers.
Do you think a cheaper Refractometer like kassoy for around 100 bucks is good enough? or is the accuratness too low compared to a Eickhorst or something similar?
Post subject: Re: refractometer with or without RI fluid?
Posted: Tue Dec 17, 2013 11:50 am
Gold Member
Joined: Thu Jan 24, 2008 4:01 pm Posts: 1902 Location: Pine City, NY and Dothan, AL
Barbra Voltaire wrote:
If the unit is not using RI liquid it is NOT a refractometer.
Is that a specialized version of the word, used by gemologists? For a student of optics, a refractometer is an instrument which measures refractive index. There are several ways of doing that, and not all of them require RI liquid.
Post subject: Re: refractometer with or without RI fluid?
Posted: Tue Dec 17, 2013 12:01 pm
Platinum Member
Joined: Tue Jan 02, 2007 8:20 pm Posts: 2659
What Barbra really meant to say (if I may presume to put words in her mouth) is "If it does not have RI liquid, then, it is not a Critical Angle Jeweler's Refractometer." This statement is true.
Reflectometers (the instrument being inquired about) don't usually use contact liquid (though there are now some high precision reflectometric refractometers that DO use RI liquid , for $10,000) measure RI indirectly using Fresnel's equations. That is an indirect measurement, measuring one quantity to deduce another. So although they have been called refractometers they really are in fact reflectometers.
There are, of course some other methods too.
Barbra if I have misinterpreted what you intended to say feel free to correct me.
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