Nanometre sized diamond powder has been purified by centrifugation to remove contamination from sp(2) bonded carbon. The purified powder has been characterized using electron energy loss spectroscopy (EELS) and Raman spectroscopy. The EELS spectra confirmed the absence of sp(2) bonded carbon and showed strong contributions from surface plasmons. Strong relatively sharp peaks are observed in the Raman spectra at 500, 1140, 1132 and 1630 cm(-1) By comparing the Raman spectra of the nanodiamond clusters with that of amorphized diamond and with calculations of the vibrational density of states we are able to suggest the origin of features in the vibrational spectrum from nanocrystalline diamond.