Diamond vs Graphite
Diamond and Graphite are commonly confused, and 4 measured properties separate them — crystal system most clearly.
Diamond vs Graphite
Diamond
C
Carbon in a cubic lattice — the hardest naturally occurring substance, and one of the best thermal conductors known.
Graphite
C
Carbon in stacked sheets — soft, slippery, electrically conductive, and chemically identical to diamond.
| Property | Diamond | Graphite |
|---|---|---|
| Crystal system Categorical values can be listed side by side but not ordered or subtracted. | cubic | hexagonal |
| Density | 3.5–3.53 g/cm³ higher | 2.09–2.23 g/cm³ |
| Lustre Categorical values can be listed side by side but not ordered or subtracted. | adamantine | metallic to dull |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | 10 higher | 1–2 |
| Refractive index Only one of the two has a figure we can stand behind, so there is nothing to compare. | 2.417 | Not known |
| Streak Only one of the two has a figure we can stand behind, so there is nothing to compare. | Not known | black |
| Thermal conductivity Only one of the two has a figure we can stand behind, so there is nothing to compare. | 900–2320 W/(m·K) | Not known |
Why these get confused
identical composition, opposite properties — the standard illustration of why structure matters
The confusion is a real and documented one, not a resemblance we have invented.