The paper presents results of investigations on floatability of synthetic diamond, natural graphite and the graphite remainings from the diamond synthesis. These investigations were broadened by measurements of zeta potentials of these materials as a function of the solution pH. Results of the studies showed that energetic state of the materials studied, evaluated on a basis of the measured "zeta" potential values, was similar. Within the entire investigated range of the pH (from ca. 2 to 10) the "zeta" potential values were negative and differences in their absolute magnitudes were of an order of a few mV. Results of flotations of the diamond and "graphite remainings from the synthesis" performed with the apolar collectors showed that the both materials floated weakly under these conditions. Yields of the diamond were below 20% and in the case of the "graphite remainings" the yields were within 25-40% depending on the pH of the flotation pulp. Natural graphite, used for the diamond synthesis, floated much better and its yields were over 75%. Results of studies on flotational and gravitational-flotational enrichment of "agglomerates", obtained after the diamond synthesis, are presented in the paper, too. These results show that the enrichment effects depend, in a significant degree, on the kind of the material processed. In the case of majority samples an application of the flotational enrichment only resulted in unsatisfactory separation of the diamond from the graphite. Much better results were obtained when the combined gravitational-flotational method of the enrichment was applied. High purity final products of graphite containing ca. 99% of the graphite were obtained in this case, with the graphite recovery of an order 90%. Final diamond products contained above 80% of the diamond and its recovery was about 96.5%.