The first order Raman line and the prominent features in the second order Raman spectrum of diamond crystals interpreted on the basis of polarization selection rules and symmetry provide energies of the critical points of the phonon dispersion curves with considerable precision. Similarly elastic constants are deduced from Brillouin shifts with high precision. Absolute Ra cross-sections are accessible from a simultaneous observation of the Raman spectrum and Brillouin components. Diamond films can be characterized on the basis of this body of information. 1.