---
title: "Fingerprint: meaning in gemology"
description: "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."
url: https://digitalgemology.com/learn/glossary/fingerprint
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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

# Fingerprint

Also called healed fracture, healed fissure

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.

## In more detail

Fingerprints are common in natural ruby and sapphire. Heating can heal fissures and leave glassy residues, which labs report. Flux-grown synthetics can also have flux fingerprints that look natural, so an expert must judge them.

## On a grading report

After heating, labs may describe residues in healed fissures as minor, moderate or significant.

## Related terms

- [Residues in healed fissures](https://digitalgemology.com/learn/glossary/residues-in-healed-fissures): Residues in healed fissures are remains of the heating process, often glassy. They stay in fissures that healed while a corundum was heated.
- [Flux growth](https://digitalgemology.com/learn/glossary/flux-growth): Flux growth is a way to grow synthetic crystals from a chemical solvent (flux). Crystals form as the hot solution slowly cools.
- [Fissure](https://digitalgemology.com/learn/glossary/fissure): A fissure is a crack in a gem, often open to the surface. Labs use the word for the cracks that fillers can enter.
- [Inclusion](https://digitalgemology.com/learn/glossary/inclusion): An inclusion is a clarity characteristic inside a diamond, or one that reaches the surface from inside.
- [Heat treatment](https://digitalgemology.com/learn/glossary/heat-treatment): Heat treatment is controlled heating of a gem to change its color or clarity.

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