There are two models the basic model doesn t have a light source. Instead of keeping the stone still. For gemologists refractive index and double refraction birefringence serve as important clues for identifying gems the following table lists these values for a variety of stones found in jewelry and gem collections. Scroll down for a chart of over 100 gems and their corresponding ri. Reliable classification and quality control of gemstones.
It exists in every doubly refractive gem but not in singly refractive or amorphous materials. Uniaxial positive uniaxial negative biaxial positive biaxial negative and without sign. We are proud to feature here the respected gem a brand of refractometer which is professional. 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 many cases up to an r. Measuring the refractive index is one of the first steps in identifying a gemstone though some gems have similar refractive indices and additional tests are required for a definitive identification.
Krüss gemstone refractometers are offered either as a compact professional or standard version. Perform a standard ri test. The refractometer is the most important gem tester after a loupe. Laminated gemstone refractometer refractive index chart of over 125 different gemstones gem refractive index chart 8 5 x 11 1 page 2 sides name structure hardness specific gravity refractive index doubly refracting bi refraction achroite tourmaline trigonal 7 5 3 06 1 62 1 64 0 018 agate chalcedony trigonal 7 2 61 1 53 1 54 0 004 this is a sample of. Refractive index or ri is one of the most important signatures of a gemstone.
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For gem identification optic character is a very useful property. The five optic characters are. It measure refractive index how far light is bent as it passes through the gemstone. Krüss offers two refractometer models designated er601 and er604 for the classification and quality control of gemstones. You can sometimes determine optic character with a polariscope.The gem n eye does this by measuring reflectivity a property closely related to refractive index and through a sophisticated algorithm converts that to a familiar refractive index value and then conducts a lookup within its internal database to find and display the matching gem s no need to convert values or cross reference to separate charts or plug into a computer because the gem n. Invest in a gemstone identification chart. Refraction is the bending of light as it passes through a gem. The gem n eye does this by measuring reflectivity a property closely related to refractive index and through a sophisticated algorithm converts that to a familiar refractive index value and then conducts a lookup within its internal database to find and display the matching gem s no need to convert values or cross reference to separate charts or plug into a computer because the gem n. For gem identification optic character is a very useful property.
Refraction is the bending of light as it passes through a gem. Krüss gemstone refractometers are offered either as a compact professional or standard version. It exists in every doubly refractive gem but not in singly refractive or amorphous materials. There are two models the basic model doesn t have a light source.
