X‐ray diffraction patterns were obtained using a tapered lead aperture. A detailed analysis of the effect of the tapered aperture is given. Experimental studies include results on W (423 GPa), on Pt (440 GPa, obtained using type IIadiamonds), and Mo (560 GPa). These results extend earlier studies in which we achieved for the first time static pressures greater than the pressure at the center of the earth.