Transparent material even beyond the hardness of diamonds

Diamond is not the world's hardest materials, superhard cubic boron nitride material is boron nitride particles  grinding wheel  into a super-hard material form, the test results show that the transparent material even beyond the diamond hardness, Vickers hardness 108GPa, and synthetic diamond Vickers hardness of 100GPa, and the material hardness of the commercial CBN twice. The future of this superhard materials with the current  cutting tools  price lower hardness CBN considerable, perhaps the future can be used for machining, milling, drilling and cutting tools.