---
title: "Heavy liquid: meaning in gemology"
description: "A heavy liquid is a dense liquid that sorts stones by specific gravity. A lighter stone floats in it, and a denser one sinks."
url: https://digitalgemology.com/learn/glossary/heavy-liquid
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Gem testing

# Heavy liquid

Also called SG liquid

A heavy liquid is a dense liquid that sorts stones by specific gravity. A lighter stone floats in it, and a denser one sinks.

## In more detail

In methylene iodide (SG 3.32), moissanite (SG 3.22) floats and diamond (SG 3.52) sinks. The liquid is toxic, so this is a laboratory method.

## Related terms

- [Specific gravity](https://digitalgemology.com/learn/glossary/specific-gravity): Specific gravity compares a stone's weight with the weight of the same volume of water. It decides how much a stone of a given size weighs.
- [Thermal diamond tester](https://digitalgemology.com/learn/glossary/thermal-diamond-tester): A thermal diamond tester measures how fast a stone draws heat from a hot tip. Diamond conducts heat very well, so it reads “diamond”.

## Learn more

- [Moissanite vs diamond: same size, different carat weight](https://digitalgemology.com/learn/diamond-vs-moissanite/moissanite-vs-diamond-carat-size)

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