http://www.sciencedirect.com/science/article/pii/S167498711000037X

The tried and tested multianvil apparatus has been widely used for high-pressure and high-temperature experimental studies in Earth science.As a result,many important results have been obtained for a better understanding of the components,structure and evolution of the Earth.Due to the strength limitation of materials,the attainable multianvil pressure is generally limited to about 30 GPa(corresponding to about 900 km of the depth in the Earth) when tungsten carbide cubes are adopted as second-stage anvils....