According to some embodiments, a method of preparing a superhard material involves using mixtures of boron with carbon nitride of C3N4 stoichiometry as precursors. The C3N4 may be nanospherical. The result of chemical interaction of these components is the formation of new ternary compound B—C—N compound with a cubic structure. According to some embodiments, the composition is BCxN, where x is about 0.5. According to some embodiments, the composition is BCxN, where x is about 0.2. According to some embodiments, the compound has a unit cell parameter a=3.645±0.005 Å. According to some embodiments, the unit cell parameter a is about 3.655 Å. Synthesis is carried out under the conditions of thermodynamic stability of diamond at pressures higher that 6.0 GPa and temperatures above 1000° C. The starting components are taken according to the following ratio: boron—20-60 wt. %, C3N4—40-80 wt. %.