---
title: "Pavilion angle: meaning in gemology"
description: "The pavilion angle is the slope of the pavilion mains, measured against the plane of the girdle."
url: https://digitalgemology.com/learn/glossary/pavilion-angle
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Anatomy and proportions

# Pavilion angle

Also called pavilion angle (degrees)

The pavilion angle is the slope of the pavilion mains, measured against the plane of the girdle.

## In more detail

It decides how much light the pavilion reflects back up, and it is the most sensitive number on a round. Tolkowsky calculated 40.75° in 1919, and GIA's Excellent limit for the pavilion alone is 40.6° to 41.8°. In our Cut Grading Tool, at a 53% table and a 34.5° crown, Excellent runs only from 40.6° to 41.4°.

## On a grading report

On the proportion diagram, in degrees, in 0.2° steps. IGI's Ideal band is 40.0 to 41.3°.

## Related terms

- [Pavilion depth](https://digitalgemology.com/learn/glossary/pavilion-depth): Pavilion depth is the depth of the pavilion, from the girdle to the culet. It is a percentage of the average diameter.
- [Pavilion main](https://digitalgemology.com/learn/glossary/pavilion-main): Pavilion mains are the 8 long facets of a round brilliant's pavilion that run from the girdle to the culet.
- [Crown angle](https://digitalgemology.com/learn/glossary/crown-angle): The crown angle is the slope of the bezel facets, measured against the plane of the girdle.
- [Critical angle](https://digitalgemology.com/learn/glossary/critical-angle): The critical angle is the angle from a facet's normal beyond which light inside a stone reflects totally. It follows from the refractive index: θc = arcsin(1/n).
- [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.

## Learn more

- [Pavilion angle and pavilion depth: how a diamond keeps the light in](https://digitalgemology.com/learn/diamond-anatomy/diamond-pavilion-angle)
- [How to read the proportion diagram on a diamond report](https://digitalgemology.com/learn/grading-reports/diamond-proportion-diagram)
- [How to read diamond proportions: decode a stone from its numbers](https://digitalgemology.com/learn/diamond-anatomy/how-to-read-diamond-proportions)

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