A diamond was a metastable allotrope of carbon. It was actually a very strong gemstone, one of the hardest substances in the world. It was also often used when making jewelry such as an engagement ring.
There were diamonds located near a volcanic fissure in Molesville, but it proved to be difficult for the Mole family to approach them, because the heat was so intense because the fissure was spewing blue flames.
- Heart of Darkness
- Quatermain diamond