Abstract <p>In the present work, an attempt is made to carry out a comprehensive theoretical analysis and interpretation of a large body of industrial and laboratory experimental data accumulated in the field of the synthesis of polycrystalline diamond of the carbonado type. The study covers the physicochemical mechanisms of phase transitions in carbon systems, barodiffusion processes, and the role of catalytic components, as well as the kinetic aspects of crystal structure growth. The analysis is based both on experimental data obtained from industrial high-pressure high-temperature (HPHT) installations and on results of targeted laboratory series in which key parameters—pressure, temperature, composition, and dwell time—were varied. Particular attention is paid to correlating industrial and laboratory results with theoretical models of phase equilibrium and growth dynamics, which not only makes it possible to explain the observed phenomena but also to propose approaches for the targeted optimization of the process.</p>