---
title: "Diamond — density, melting point and properties"
description: "Diamond has a density of 3,515 kg/m³. Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/diamond/
site: "At One Place"
---

# Diamond

**Density of diamond: 3,515 kg/m³**

3.52 g/cm³ · 219.4 lb/ft³

The hardest known material at Mohs 10, and the scale is badly non-linear — diamond is several times harder than corundum at 9, not 11% harder. It has no melting point at ordinary pressure: heated in air it burns from about 700 °C, and in an inert atmosphere it converts to graphite rather than melting, because graphite is the thermodynamically stable form at 1 atm. Less famously, it conducts heat about five times better than copper, which is why it is used as a heat spreader under high-power laser diodes.

## Properties

- **Density:** 3,515 kg/m³ — 3.52 g/cm³
- **Young's modulus:** 1050 GPa
- **Thermal conductivity:** 2000 W/(m·K)
- **Hardness:** 10 Mohs
- **Thermal expansion:** 1 µm/(m·K)
- **Floats in water:** No
- **Magnetic:** No

## What it is used for

- Cutting, grinding and drilling tooling
- Gemstones
- Heat spreaders in high-power electronics
- Anvils for ultra-high-pressure research

## How it compares

*Water is 1,000 kg/m³. Anything with a shorter bar than water floats in it.*

- air: 1.2 kg/m³
- expanded polystyrene foam: 20 kg/m³
- rigid polyurethane foam: 40 kg/m³
- Water — the float line: 1,000 kg/m³
- diamond: 3,515 kg/m³
- tungsten: 19,250 kg/m³
- gold: 19,300 kg/m³
- platinum: 21,450 kg/m³

*Water is 1,000 kg/m³. Anything below that floats.*

| Material | Density | Relative to water |
| --- | --- | --- |
| rigid polyurethane foam | 40 kg/m³ | 0.04× |
| expanded polystyrene foam | 20 kg/m³ | 0.02× |
| air | 1.2 kg/m³ | 0.00× |
| diamond ← | 3,515 kg/m³ | 3.52× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

Diamond contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

## Is it magnetic?

Diamond is not a metal and has no ferromagnetic response.

## Common questions

### What is the density of diamond?

3,515 kg/m³, or 3.52 g/cm³.

### Does diamond float?

No. At 3,515 kg/m³ it is denser than water.

### Is diamond magnetic?

Diamond is not a metal and has no ferromagnetic response.

## Related pages

- [Does diamond float?](https://atoneplace.net/does-it-float/diamond/)
- [Granite](https://atoneplace.net/material/granite/)
- [Marble](https://atoneplace.net/material/marble/)
- [Quartz](https://atoneplace.net/material/quartz/)
- [Limestone](https://atoneplace.net/material/limestone/)
- [Slate](https://atoneplace.net/material/slate/)
- [Sandstone](https://atoneplace.net/material/sandstone/)

## Sources

- United States Geological Survey — USGS (https://www.usgs.gov/) [Public domain (US Government)]