In 2009 ultra-hard diamond-like BC 5 was synthesized by Solozhenko et al. . This phase corresponds to the ultimate solubility of boron in diamond and possesses Vickers hardness of 71 GPa, unusually high for superhard materials fracture toughness (~10 MPa•m½), and very high (up to 1900 K) thermal stability which makes it an exceptional superabrasive superior to diamond. Diamond-like BC 5 is metastable phase and can be synthesized only in a narrow temperature range under pressures above 20 GPa which makes its production quite a challenge.