---
title: "Tilt (light performance): meaning in gemology"
description: "Tilt is how much of its face-up brilliance a cut keeps when the stone tilts. Our tilt score compares brilliance at a 20° tilt with brilliance face-up,…"
url: https://digitalgemology.com/learn/glossary/tilt-light-performance
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

> Markdown copy of https://digitalgemology.com/learn/glossary/tilt-light-performance. 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

# Tilt (light performance)

Also called tilt retention, tilt score

Tilt is how much of its face-up brilliance a cut keeps when the stone tilts. Our tilt score compares brilliance at a 20° tilt with brilliance face-up, capped at 100.

## In more detail

A stone on a hand is seldom seen exactly face-up. A cut that holds its light when tipped looks steadier. The cap at 100 stops a dim cut from scoring well only because it has little light to lose. The T73 round brilliant in diamond scores 92.

## How we measure it

The census runs again with the stone tilted 20°, with 2,200 rays. T = min(100, 100 × B(20°) ÷ B(0°)). The Brightness & Tilt Analysis gives a fuller picture: its figures at 13 tilts from −30° to 30°.

## Related terms

- [Brilliance](https://digitalgemology.com/learn/glossary/brilliance): Brilliance is the white light that a cut stone returns to the viewer. In our census, it is the share of entering light that leaves through the crown toward the viewer.
- [Light census](https://digitalgemology.com/learn/glossary/light-census): The light census is our ray tracer behind the Cut Performance Wheel, the cut-page scores and the Cut Performance Index. It drops a fixed set of rays on a stone from above and counts where each one leaves.
- [Brightness & Tilt Analysis](https://digitalgemology.com/learn/glossary/brightness-and-tilt-analysis): The Brightness & Tilt Analysis is a free Digital Gemology tool. It measures how much dome light a cut returns face-up, and how this changes with tilt.
- [Overall score](https://digitalgemology.com/learn/glossary/overall-score): The overall score is one figure out of 100 that combines our light-performance scores for one cut in one gemstone. The Cut Performance Wheel calls it Global.
- [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.

## Learn more

- [Cut Performance Wheel and cut-page scores](https://digitalgemology.com/about/how-we-measure/performance-wheel)
- [Digital Gemology Cut Performance Index](https://digitalgemology.com/learn/cut-performance-index)
- [Brightness & Tilt Analysis](https://digitalgemology.com/about/how-we-measure/brightness-tilt)

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