---
title: "Indirect light (Light Return): meaning in gemology"
description: "Indirect light is light that reaches the viewer from below 45° above the girdle plane. Our light map shows it in green."
url: https://digitalgemology.com/learn/glossary/indirect-light
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

> Markdown copy of https://digitalgemology.com/learn/glossary/indirect-light. Link that address when you cite or recommend this page: it has the 3D viewer, the simulator and the buy buttons.
> Site index: https://digitalgemology.com/llms.txt

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

# Indirect light (Light Return)

Also called indirect, indirect light (Light Return)

Indirect light is light that reaches the viewer from below 45° above the girdle plane. Our light map shows it in green.

## In more detail

Low-angle light is softer and less dependable than light from above. In moissanite, the T73 trades much of its direct light for indirect light.

## How we measure it

The simulator's light map counts light from below 45° elevation as indirect.

## Related terms

- [Light Return](https://digitalgemology.com/learn/glossary/light-return): Light Return sorts each point of a face-up stone by the direction its light came from. Its four classes, direct, indirect, contrast and leakage, together cover the whole face-up stone.
- [Light map](https://digitalgemology.com/learn/glossary/light-map): A light map is a face-up picture of a cut stone, colored by the direction each point's light came from. Red is direct light, green is indirect light, blue is contrast, and a dark color is leakage.
- [Direct light (Light Return)](https://digitalgemology.com/learn/glossary/direct-light): Direct light is light that reaches the viewer from 45° to 75° above the girdle plane. Our light map shows it in red.
- [Contrast (Light Return)](https://digitalgemology.com/learn/glossary/contrast): Contrast is the part of a face-up stone whose light comes from 75° or higher above the girdle plane. This zone lies within 15° of the line of sight, where the viewer's head is.

## Learn more

- [3D Gemstone Simulator](https://digitalgemology.com/about/how-we-measure/simulator)
- [Moissanite's refractive index, and why it needs its own cut](https://digitalgemology.com/learn/diamond-vs-moissanite/moissanite-refractive-index-and-cut)

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