Optical Property · Reviewed definition

Birefringence

The numerical difference between principal refractive indices in an anisotropic material.[1]

Also known as: Double Refraction

Plain English

What it means

Some crystals interact with light differently by direction and therefore have more than one principal RI.

Why it matters

It helps characterize optical behavior and can support identification.

What it does not tell you

It does not apply in the same way to isotropic materials.

Evidence

References

  1. 1
    Analysis of Gemstones at GIA Laboratories

    Gemological Institute of America

    Open source