---
title: "Ideal cut: meaning in gemology"
description: "\"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…"
url: https://digitalgemology.com/learn/glossary/ideal-cut
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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

# Ideal cut

Also called Ideal, Excellent-Ideal, Ideal Cut Round Brilliant, ideal proportions

"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".

## In more detail

IGI's May 2023 Ideal band starts with total depth 58.5 to 62.5% and table 53 to 60%. The crown angle must be 33 to 36° and the crown height 13 to 16.5%. The pavilion must be 40.0 to 41.3° and 42 to 44% deep, with a Thin to Slightly Thick girdle. Polish and symmetry must be at least Very Good.

## On a grading report

IGI writes "Ideal Cut Round Brilliant" as a comment beside an Excellent cut grade. GIA prints no Ideal cut grade.

## Related terms

- [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.
- [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.
- [Triple Excellent](https://digitalgemology.com/learn/glossary/triple-excellent): Triple Excellent is trade shorthand for a GIA round brilliant with Excellent cut, Excellent polish and Excellent symmetry.
- [Tolkowsky ideal cut](https://digitalgemology.com/learn/glossary/tolkowsky-ideal-cut): The Tolkowsky ideal cut is the round brilliant that Marcel Tolkowsky calculated in his 1919 book Diamond Design. It has a 40.75° (40° 45′) pavilion, a 34.5° (34° 30′) crown and a 53% table.

## Learn more

- [What "ideal cut" means on a diamond report](https://digitalgemology.com/learn/grading-reports/what-ideal-cut-means)
- [How to read a diamond grading report, start to finish](https://digitalgemology.com/learn/grading-reports/how-to-read-a-diamond-grading-report)

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