A large number of commercially obtained diamonds were examined using Raman/PL,FTIR,deep UV-excited PL,Optically Stimulated Luminescence(OSL) and electronic absorption.Using 532 nm excited PL spectra the CVD diamonds were categorized as per the intensity of SiV signal which was accepted as one of the diagnostic centre of CVD growth.The diamonds which were heavily doped with silicon,as seen by the intensity of SiV signal at 737 nm,had exhibited relatively large optical inertness for UV excitation.