According to Chemistry 
there's a difference between "tenacity" and "hardness". Diamonds are very hard, which means they cannot be scratched, but they're not tenacious, which means they can be broken almost as easily as ordinary glass. It's not possible, then. Is that what you're talking about? 
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“The scar had not pained Harry for nineteen years. All was well.” HP and the Deathly Hallows "Why's it always the hat photograph?"The Reichenbach Fall
