Diamond is the hardest natural material on earth. It scores 10 on the Mohs scale - nothing found in nature scratches it. And yet, given enough heat, it will burn.
Diamond is pure carbon, the same element as graphite and charcoal. At around 700 degrees Celsius in the presence of oxygen, a diamond will begin to oxidise and eventually combust - converting to carbon dioxide and disappearing entirely. No ash, no residue. Just gas.
This is not a theoretical observation. Jewellers know it. They work carefully with diamonds near heat sources. A torch applied too close to a mounted diamond during sizing or repair can, if the jeweller isn't careful, burn away part of the stone.
The ancient Romans knew something about this, though they didn't understand the chemistry. They called diamond "adamas" - unconquerable - and believed it was indestructible. For most practical purposes, they weren't wrong. Under normal conditions, nothing you encounter in daily life can damage a diamond. It's harder than any tool available to you.
But normal conditions aren't all conditions.
This creates an odd split identity for the stone. In hardness, it's supreme. In one specific dimension - heat in an oxidising environment - it's surprisingly vulnerable. The same carbon bonding that makes diamond impossibly hard also makes it chemically similar to coal. Push it to the right conditions and the "indestructible" stone evaporates.
There's a broader lesson somewhere in this: things that seem absolutely permanent often have a specific weakness. Diamond included. Before choosing a diamond ring, our education page has practical care advice.
