Two shock wave experiments employing inclined mirrors have been carrried out to determine the Hugoniot elastic limit (HEL), final shock state at 191 and 217 GPa, and the post-shock state of diamond crystal, which is shock-compressed along the intermediate direction between the ⟨111⟩ and ⟨110⟩ crystallographic axes. The HEL wave has a velocity of 19.9¿0.3 mm/&mgr;sec and an amplitude of 63¿28 GPa. An alternate interpretation of the inclined wedge mirror steak record suggests a ramp precursor wave and then another HEL value. The maximum post-shock density achieved upon release from the ~200 GPa shock state is ~3.95 Mg/m3, which compares to the initial density 3.52 Mg/m3. This result suggests an elastic unloading effect or shock-induced transition to a denser (possibly metallic) phase.