A Gemological Refractometer is your primary and most powerful tool in gemstone identification.  As with any typical critical angle refractometer, it will measure the Refractive Index of faceted stones, transparent to near opaque, whether loose or mounted (in most cases), up to an R. I. value of 1.81. 

Your refractometer kit comes with a bottle of Refractive Index Liquid with a matching R.I. value of 1.81 (see photo at right), as well as a built-in light with On/Off switch, in combination with an integrated Monochromatic Filter precluding the need for a special monochromatic illuminating light.  The unit's compound eyepiece includes a Polarizing Filter for precise measurement of Birefringence, and a built-in magnifying lens.

To use the refractometer, open the lid, then place a small amount of R.I. fluid on the refractometer's measuring glass using the bottle's built-in dropper.  This fluid is necessary to create an optical contact between the glass and the gemstone.  Then place a flat polished facet of your stone on the measuring glass and close the lid of the refractometer to shield out extraneous light.  Turn on the illuminating light at the back of the instrument.  Then look through the eyepiece and read the scale at the point of division between the lighted portion and the shadowed portion created by the critical angle of the particular gemstone.

If the gemstone is doubly refractive, best seen by rotating the polarizing filter as you view the scale, you will see 2 shadow lines, the numerical difference between them equating to that stone's birefringence.  As an example, the stylized drawing of the refractometer scale at right shows an R.I. value of 1.654 to 1.689 and thus Birefringence of .035, probably identifying this stone as Peridot.

This refractometer is made in Russia.  Dimensions are 4.5" Deep x 1.5" Wide x 2.5" High.  It comes with a padded Carrying Case (see photo at left), along with instructions in English, while a handy laminated chart listing both R.I. and Birefringence values for popular gemstones are included (see photo of one below).

 

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We also offer an economy Gem Refractometer, and replacement bottles of Refractive Index Fluid.  Click on these links or on the navigation buttons at top for more information.

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