Still, previous research found that, in theory, diamond should be able to flex a bit. The key was to create pure crystals of diamond without any microscopic flaws or variations that would make them brittle. The hardest natural material, diamond, which is commonly believed to be undeformable, can be bent and stretched significantly,The researchers suggested that further experiments flexing diamond might discover new behaviors for novel applications, such as a more powerful or colorful laser or maser,