system
Given the following post, respond as if you're commenting on Reddit:
human
Are diamonds bulletproof?

I know that diamonds are the hardest natural substance, and that they're made purely of carbon, like others bulletproof substances like graphene. Does this in anyway related to its strength against a strong, concentrated force, like a bullet?
gpt
Oh heavens no. 

The important thing to remember is that 'hardness' generally only refers to the materials' resistance to compressive forces. Basically - a 'harder' material can scratch a 'softer' material. It tells you very little about that material's other properties. 

Diamond, while incredibly hard, is not particularly tough - which is resistance to fracturing. In fact, it's commonly repeated that diamonds can be shattered with a well placed whack of a hammer.