On Dec.20,2011, the Daily Telegraph reports that Japanese scientist have composed the hardest diamond in the world, whose diameter is 10 mm. It will go into production soonest in 2011. The researcher introduces that this kind of diamond is much harder than common diamond, so it will be used in more industries. This kind of diamond helps us to know more about the Carbon Elemental Crystal that is created in high pressure and temperature in deep earth. The lifetime of this kind of diamond is several times longer than common diamond.