---
title: "Spread (light performance): meaning in gemology"
description: "Spread is an estimate of a cut's face-up size for its weight, compared with a stone 61.5% deep. Above 100 means the cut faces up larger for its weight than…"
url: https://digitalgemology.com/learn/glossary/spread-score
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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

# Spread (light performance)

Also called face-up size per carat (estimate)

Spread is an estimate of a cut's face-up size for its weight, compared with a stone 61.5% deep. Above 100 means the cut faces up larger for its weight than that reference.

## In more detail

Weight goes with the cube of the diameter, so the formula uses the cube root of the depth ratio. Spread estimates from depth alone. The face-up size on our gemstone cut pages is measured from each model's outline instead.

## How we measure it

Spread = min(130, 100 × (61.5 ÷ depth)^(1/3)), with depth as a percentage of the width. It is the same in every gemstone. The Cut Performance Wheel draws values above 100 on its 100 ring and lists the true figure.

## Related terms

- [Face-up size](https://digitalgemology.com/learn/glossary/face-up-size): Face-up size is how large a stone looks from above for its weight. Two stones of the same carat weight can differ in face-up size because of their depth and shape.
- [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.
- [Cut Performance Wheel](https://digitalgemology.com/learn/glossary/cut-performance-wheel): The Cut Performance Wheel is a free Digital Gemology tool. It draws eight light-performance scores of one cut, in one gemstone, on a wheel.
- [Total depth](https://digitalgemology.com/learn/glossary/total-depth): Total depth is the height of a stone from table to culet as a percentage of its average diameter. It equals crown height + girdle thickness + pavilion depth.
- [Carat weight](https://digitalgemology.com/learn/glossary/carat-weight): Carat weight is the weight of a gemstone. One carat is 200 milligrams, a fifth of a gram, and it has 100 points.

## 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)

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