In this work we present experimental results on the behavior of diamond at Megabar pressure. The experiment was performed using the PHELIX facility at GSI in Germany to launch a planar shock into solid multi-layered diamond samples. The target design allows to measure shock velocity in diamond and in two metal layers and to measure the free surface velocity after shock breakout. As diagnostics, we used two VISAR systems (velocity interferometry system for any reflector). Our measurements show that for the pressures obtained in diamond (between 9 and 3 Mbar), the propagation of the shock induces a reflecting state of the material. Finally experimental results were compared to hydrodynamical simulations in which we used different equations of state, showing compatibility with dedicated Sesame tables for diamond.