Lesson 4: Refractometer Guide, Part 1: Refractive Index Testing

Step 3: Practical Gemology

Lesson 4


Gemstone identification is like detective work. You gather clues and eliminate suspects until you’re left with clues that lead to only one suspect … or gemstone. Since few gems share the same refractive index or RI, testing an unknown gem’s RI is a good way to start an investigation. The gem refractometer is the most straightforward and accurate tool for refractive index testing. Our three-part refractometer guide will show prospective gemologists and interested hobbyists how to use a refractometer to conduct RI testing as well as other gem identification tests.

Inside The Refractometer

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 …

Every Gemstone Is Unique - Here's How The Experts Evaluate Them

in this training-course, discover the tools, tests & valuation process used by expert gemologists for colored gemstones, opals & diamonds

Course: Hands-On Gemology: Gemstone Identification Grading & Testing
Purchase Course: $79.00
Skill Level: Intermediate - Advanced
Lessons: 60
Time: 480 min