Gemological Instrument · Reviewed definition

Refractometer

A gemological instrument used to determine refractive index from critical-angle behavior at an optical contact.[1]

Plain English

What it means

A refractometer converts a light-boundary observation into an RI reading.

Why it matters

It is a standard tool for colored-stone identification.

What it does not tell you

Instrument range, surface geometry, optical contact, and operator interpretation constrain readings.

Evidence

References

  1. 1
    Analysis of Gemstones at GIA Laboratories

    Gemological Institute of America

    Open source