---
title: "Round brilliant: meaning in gemology"
description: "A round brilliant is a round diamond with the brilliant facet plan. It has 33 crown and 24 pavilion facets: 57 in all, or 58 with a culet."
url: https://digitalgemology.com/learn/glossary/round-brilliant
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Cuts and shapes

# Round brilliant

Also called standard round brilliant, round brilliant cut, RBC, SRB, round

A round brilliant is a round diamond with the brilliant facet plan. It has 33 crown and 24 pavilion facets: 57 in all, or 58 with a culet.

## In more detail

It is the most common shape. GIA gives a cut grade only to standard round brilliants in the D-to-Z range. Most are now finished with a faceted girdle, which is counted separately. Its proportions go back to Tolkowsky's 1919 calculation.

## On a grading report

Written "Round Brilliant" in the shape and cutting style line.

## Related terms

- [Brilliant cut](https://digitalgemology.com/learn/glossary/brilliant-cut): A brilliant cut is a cutting style with a crown of facets above a pavilion. Its facet angles return light and spread it into fire.
- [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.
- [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.
- [Facet](https://digitalgemology.com/learn/glossary/facet): A facet is one flat, polished face of a cut gemstone. Its angle and its direction around the stone decide where it sends light.
- [Fancy shape](https://digitalgemology.com/learn/glossary/fancy-shape): A fancy shape is any diamond outline other than round, such as oval, pear, marquise, cushion, princess or emerald.

## Learn more

- [The parts of a diamond: crown, girdle and pavilion](https://digitalgemology.com/learn/diamond-anatomy/parts-of-a-diamond)
- [The grades on a diamond report: color, clarity and cut](https://digitalgemology.com/learn/grading-reports/diamond-report-grades)
- [T73 Round Brilliant Cut](https://digitalgemology.com/cuts/t73-round-brilliant)

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