Stuff Matters: Exploring the Marvelous Materials That Shape Our Man-Made World

by Mark Miodownik

“How long will the concrete take to dry, do you think?” a man with a dog asked me, while we were both peering through the viewing window of the hoardings. “I dunno,” I lied. My lie was intended to cut the conversation short, which it did. It was a habitual lie, born of living in London and finding ways of politely avoiding talking to strangers. Especially as I didn’t know how he, or his dog, would take to my beginning our acquaintance by correcting him: concrete doesn’t dry out.

But diamonds are not forever, at least on the surface of this planet. It is, in fact, diamond’s sibling structure, graphite, that is the more stable form, and so all diamonds, including the Great Star of Africa in the Tower of London, are actually turning slowly into graphite. This is distressing news for anyone who owns a diamond, although they can be reassured that it will take billions of years before they see an appreciable degradation of their gems.