“Anyway, I hear the entire Dianoid building is made of diamond. Are they messing with us or something?”
“Your information’s gotten twisted after an unintentional game of telephone there, nyah. It’s technically made of carbon materials like carbon fiber, carbon frames, and carbon nanotubes which have some artificial diamond inside[…]”

Toaru Majutsu no Index New Testament vol. 12 ch.1 pt.5