The effect of high temperature on sulfide inclusions in diamonds was studied. The object of study was sulfide-bearing diamond crystals from Yakutian kimberlite pipes. The experiments were carried out on a multiple anvil apparatus BARS with a solid-phase refractory oxide cell at 5.0 GPa and 1000–1600 °C. In the temperature range from 1350 to 1450 °C, the crack rosettes around sulfide inclusions in diamond crystals were decolorized but the position of inclusions in diamond crystals did not change. The “decolorization” seems to be due to the fact that disseminated sulfide particles were molten, consolidated, and then removed from the cracks. At a higher temperature (1600 °C) inclusions turned black as a result of diamond graphitization.