---
title: "Fissure: meaning in gemology"
description: "A fissure is a crack in a gem, often open to the surface. Labs use the word for the cracks that fillers can enter."
url: https://digitalgemology.com/learn/glossary/fissure
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Clarity characteristics

# Fissure

Also called fracture (clarity), surface-reaching fracture

A fissure is a crack in a gem, often open to the surface. Labs use the word for the cracks that fillers can enter.

## In more detail

Almost all emeralds have fissures, and cutters plan around them. A surface-reaching fissure can weaken a stone. It also lets oil, resin or glass in, which makes it harder to see.

## On a grading report

Filled fissures are reported with the filler and its degree: minor, moderate or significant.

## Related terms

- [Clarity enhancement](https://digitalgemology.com/learn/glossary/clarity-enhancement): Clarity enhancement is filling surface-reaching fissures with a filler such as oil, resin, wax or glass, so they show less.
- [Emerald oiling](https://digitalgemology.com/learn/glossary/emerald-oiling): Emerald oiling is filling an emerald's fissures with a colorless oil to make them less visible.
- [Lead-glass filling](https://digitalgemology.com/learn/glossary/lead-glass-filling): Lead-glass filling is a treatment that fills fissures and cavities in corundum, mostly ruby, with high-lead glass to hide them.
- [Fingerprint](https://digitalgemology.com/learn/glossary/fingerprint): A fingerprint is a pattern of tiny fluid or glassy drops left where a crack inside the crystal healed. It often looks like a human fingerprint.
- [Toughness](https://digitalgemology.com/learn/glossary/toughness): Toughness is a gem's resistance to chipping and breaking. It differs from hardness, which is resistance to scratching.

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