---
title: "Contrast (Light Return): meaning in gemology"
description: "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…"
url: https://digitalgemology.com/learn/glossary/contrast
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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

# Contrast (Light Return)

Also called head-shadow contrast, contrast (Light Return)

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.

## In more detail

The light map shows contrast in blue. These areas reflect the viewer's head, so in real light they often look dark. In a well-cut round they form a crisp, even pattern that gives the stone sharpness. Contrast is not leakage: leakage areas look out of the back of the stone.

## How we measure it

The simulator's light map counts light from 75° elevation and above as contrast. The Brightness & Tilt Analysis and the Cut Grading Tool use the same zone.

## 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.
- [Head shadow](https://digitalgemology.com/learn/glossary/head-shadow): The head shadow is the part of the overhead light that the viewer's own head blocks. In our tools, it is a cone around the line of sight in which no light counts.
- [Leakage](https://digitalgemology.com/learn/glossary/leakage): Leakage is light that enters a stone and leaves where the viewer cannot see it, mostly through the pavilion. Lower leakage is better.
- [Bow-tie](https://digitalgemology.com/learn/glossary/bow-tie): A bow-tie is a dark band across the belly of an oval, pear, marquise or other elongated stone. It is not an inclusion or a color: the facets there send little light back to the viewer.

## Learn more

- [3D Gemstone Simulator](https://digitalgemology.com/about/how-we-measure/simulator)
- [What causes a bow-tie? Four explanations, tested](https://digitalgemology.com/learn/bow-tie/what-causes-a-bow-tie)

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