What is the hardest material on earth?
Diamond is the hardest naturally occurring substance found on Earth. But it is not the hardest substance. Wurtzite boron nitride (synthetic) and lonsdaleite (which comes from meteorites) are both harder.
But, This is little bit controversial as scientists are working on this and found out that there are so many materials which are stronger than Diamond.
Currently, diamond is regarded to be the hardest known material in the world. But by considering large compressive pressures under indenters, scientists have calculated that a material called Wurtzite Boron Nitride (w-BN) has a greater indentation strength than diamond.