---
title: "Light Performance Report (IGI): meaning in gemology"
description: "IGI's Light Performance Report is an extra report for round diamonds with top optical performance. It gives a light performance score with sub-scores and an…"
url: https://digitalgemology.com/learn/glossary/igi-light-performance-report
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Grading report

# Light Performance Report (IGI)

Also called IGI Light Performance Report

IGI's Light Performance Report is an extra report for round diamonds with top optical performance. It gives a light performance score with sub-scores and an Ideal-Scope image made by ray tracing.

## In more detail

It uses only the stone's external proportions, so it doesn't account for heavy inclusions. Our brilliance, fire and scintillation scores are a different measure, from our own models.

## On a grading report

A separate IGI report, issued with the grading report.

## Related terms

- [AGS Ideal Report by GIA](https://digitalgemology.com/learn/glossary/ags-ideal-report): The AGS Ideal Report by GIA is a digital supplement to a GIA report. It gives the American Gem Society's light performance grade, and only AGS Ideal 0 stones get one.
- [Ideal cut](https://digitalgemology.com/learn/glossary/ideal-cut): "Ideal cut" has three meanings: an IGI comment, a GIA supplement grade, or a sales word. At IGI it marks an Excellent round with narrower proportions; at GIA it appears only as "AGS Ideal".
- [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.
- [Fire](https://digitalgemology.com/learn/glossary/fire): Fire is the flashes of spectral color that a cut stone sends out. In our census, fire is the share of returned light whose colors leave more than 0.6° apart.
- [Cut grade](https://digitalgemology.com/learn/glossary/cut-grade): The cut grade rates how well a diamond's proportions and finish work, from Excellent to Poor. GIA gives it only to standard round brilliants in the D-to-Z color range.

## Learn more

- [What "ideal cut" means on a diamond report](https://digitalgemology.com/learn/grading-reports/what-ideal-cut-means)

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