An improved high pressure apparatus and related methods for processing supercritical fluids. In a specific embodiment, the present apparatus includes a capsule, a release sleeve, a heater, at least one ceramic segment or ring but can be multiple segments or rings, optionally, with one or more scribe marks and/or cracks present. In a specific embodiment, 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. In a specific embodiment, the apparatus is capable of accessing pressures and temperatures of 0.2-2 GPa and 400-1200° C., respectively. Following a run, the release sleeve may be at least partially dissolved or etched to facilitate removal of the capsule from the apparatus.