---
title: "Jones calculus: meaning in gemology"
description: "Jones calculus is a matrix method for following polarized light through filters, retarders and crystals. R.C. Jones published it in 1941."
url: https://digitalgemology.com/learn/glossary/jones-calculus
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Optics

# Jones calculus

Jones calculus is a matrix method for following polarized light through filters, retarders and crystals. R.C. Jones published it in 1941.

## In more detail

Each element is a 2 × 2 matrix acting on the light's vibration. Between crossed polarizers, a plain retarder passes I = sin²2φ sin²(γ/2) of the light. Here φ is the turn of the retarder and γ is its retardance.

## How we measure it

The Polariscope computes everything by Jones calculus at 81 wavelengths. It uses the refractive indices and measured absorption of each stone.

## Related terms

- [Polariscope](https://digitalgemology.com/learn/glossary/polariscope): A polariscope is a gem-testing instrument with a stone between two polarizing filters. With the filters crossed, it shows whether a stone is singly refractive, doubly refractive, strained or an aggregate.
- [Polarized light](https://digitalgemology.com/learn/glossary/polarized-light): Polarized light vibrates in one direction across its path, instead of in every direction. A polarizing filter passes only the light that vibrates along its own direction.
- [Birefringence](https://digitalgemology.com/learn/glossary/birefringence): Birefringence is the difference between the two refractive indices of a doubly refractive stone. It shows how strongly the stone splits light into two rays.

## Learn more

- [Polariscope](https://digitalgemology.com/about/how-we-measure/polariscope)

[All 328 terms](https://digitalgemology.com/learn/glossary)