A high pressure apparatus and related methods for processing supercritical fluids is described. The apparatus includes a capsule, a heater, at least one ceramic ring with one or more scribe marks and/or cracks present. The apparatus optionally has a metal sleeve containing each ceramic ring. The apparatus also has a high-strength enclosure, end flanges with associated insulation, and a power control system. The apparatus is capable of accessing pressures and temperatures of 0.2-2 GPa and 400-1200° C., respectively.