---
title: "Residues in healed fissures: meaning in gemology"
description: "Residues in healed fissures are remains of the heating process, often glassy. They stay in fissures that healed while a corundum was heated."
url: https://digitalgemology.com/learn/glossary/residues-in-healed-fissures
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Treatments and origin

# Residues in healed fissures

Also called flux healing, FAH

Residues in healed fissures are remains of the heating process, often glassy. They stay in fissures that healed while a corundum was heated.

## In more detail

LMHC labs rate the amount as minor, moderate or significant. The residue ranges from fine 'bubbles' to thick films. Glass-filled cavities can also be present. Lead-glass filling is a different treatment, with its own wording.

## On a grading report

Indications of heating, with residues rated FAH 1 (minor), FAH 2 (moderate) or FAH 3 (significant). Filled cavities get their own code, such as FAH C3.

## Related terms

- [Indications of heating](https://digitalgemology.com/learn/glossary/indications-of-heating): 'Indications of heating' (H) is the standard LMHC lab wording for a corundum that shows signs of heat treatment. The heating changed its color or transparency.
- [Heat treatment](https://digitalgemology.com/learn/glossary/heat-treatment): Heat treatment is controlled heating of a gem to change its color or clarity.
- [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.
- [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.

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