The intensity distribution between reflexes in six-wave symmetric case of diffraction of CuKα1 radiation was experimentally investigated with the help of double-block monolithic crystal system. It was shown that the multiwave reflexes obtained for germanium single crystal were divided by intensity in three groups, and after the second block 20 multiwave reflexes (beams) out of the obtained number of 36 ones were ‘pure’, i. e., not accompanied with two-wave backgrounds. A technique of precision measurements in the field of multiwave diffraction is proposed.