A gem refractometer is the best tool for refractive index testing. Learn how to use this instrument to conduct this and other gem identification tests.
12 Minute Read
All refractometers function in the same way, though they may look slightly different than the one pictured here.
A rear window allows light to enter. A hinged cover allows you to place a gem inside, on the flat side of a hemicylinder made of special, high RI glass. The viewing lens in front magnifies the scale. The lens has a polarizing filter that can be rotated. Both the filter and the lens are removable.
The gem’s shadow is directed to the scale, and the RI is read where the shadow line falls.
To measure the RI of a faceted gem with a refractometer:
For more specific instructions on precisely locating the RI, see “Finding the Green Shade Cutoff” below.
For refractive index testing procedures for…
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All refractometers function in the same way, though they may look slightly different than the one pictured here.
A rear window allows light to enter. A hinged cover allows you to place a gem inside, on the flat side of a hemicylinder made of special, high RI glass. The viewing lens in front magnifies the scale. The lens has a polarizing filter that can be rotated. Both the filter and the lens are removable.
The gem’s shadow is directed to the scale, and the RI is read where the shadow line falls.
To measure the RI of a faceted gem with a refractometer:
For more specific instructions on precisely locating the RI, see “Finding the Green Shade Cutoff” below.
For refractive index testing procedures for…
A gem refractometer is the best tool for refractive index testing. Learn how to use this instrument to conduct this and other gem identification tests.
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