---
title: "Lower half length: meaning in gemology"
description: "Lower half length is how far the lower half facets reach from the girdle toward the culet. It is a percentage of that distance."
url: https://digitalgemology.com/learn/glossary/lower-half-length
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Anatomy and proportions

# Lower half length

Also called lower girdle facet length, LGF %, lower half %

Lower half length is how far the lower half facets reach from the girdle toward the culet. It is a percentage of that distance.

## In more detail

GIA's Excellent range is 70 to 85% and its Very Good range 65 to 90%. By a common rule of thumb, about 75% or less gives fatter hearts in a hearts and arrows viewer. At 80% or more, the hearts are thinner and further apart. The T73's lower halves are at 77%.

## On a grading report

On the proportion diagram; GIA reports it to the nearest 5%.

## Related terms

- [Lower half facet](https://digitalgemology.com/learn/glossary/lower-half-facet): Lower half facets are the 16 long, thin triangles along the pavilion edge of a round brilliant. There are two between each pair of pavilion mains.
- [Star length](https://digitalgemology.com/learn/glossary/star-length): Star length is how far the star facets reach from the table edge toward the girdle. It is a percentage of that distance.
- [Hearts and arrows](https://digitalgemology.com/learn/glossary/hearts-and-arrows): Hearts and arrows is a pattern that a precisely cut round brilliant shows in a reflector viewer. Face-up it shows eight arrows, and face-down eight hearts.
- [Pavilion main](https://digitalgemology.com/learn/glossary/pavilion-main): Pavilion mains are the 8 long facets of a round brilliant's pavilion that run from the girdle to the culet.

## Learn more

- [Star length and lower half length in a round brilliant](https://digitalgemology.com/learn/diamond-anatomy/star-length-and-lower-half-length)
- [How to read the proportion diagram on a diamond report](https://digitalgemology.com/learn/grading-reports/diamond-proportion-diagram)
- [Hearts and arrows diamonds: precision you can see](https://digitalgemology.com/learn/historic-cuts/hearts-and-arrows-diamonds)

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