Chinese scientists have created a diamond with no Achilles’ heel – one that cannot be broken, even by a hard knock with a hammer – according to a paper published in the peer-reviewed journal Nature Synthesis. While a diamond is the hardest natural material on Earth, it has a major weakness. It is brittle, like glass, and a sharp blow can shatter it. For years, scientists have tried to make diamonds tougher without losing their legendary hardness. Typically, increasing one characteristic has...