Usually, the production of superhard materials with low-defective crystal structure requires the high pressure-high temperature conditions of synthesis or of subsequent sintering. In the case of metastable phases such as BC₅, the temperature and time of synthesis should be well controlled. Currently available superhard phases show either low thermal and chemical stability (diamond), or remarkably low hardness as compared to diamond (cBN). Recently, a novel method has been developed for production of nanostructured B-C phases using various techniques including quasi-hydrostatic, uniaxial and shock compression.