This study is devoted to clarifying the crystal structure of diamond particles synthesized by shock wave compression of graphite. Employing a comprehensive suite of methods including energy-dispersive X-ray spectroscopy, XRD, TEM and SEM, laser diffraction, DLS, Raman spectroscopy, nitrogen adsorption-desorption analysis, and SAXS, the research determines the particle size distributions, elucidates the nanocrystalline structure of the diamond particles, and characterizes their impurity compositions. The findings demonstrate that the intrinsic structural differences between diamond produced by detonation of explosives and those obtained through shock wave compression of graphite lead to a significantly lower efficiency of thermal disaggregation for the latter particles. Moreover, inclusions of hexagonal diamond (2H), also known as lonsdaleite, were observed within the crystal structure of the studied particles.