Results of investigation of large diamond samples from main primary and some placer deposits of Yakutia by FTIR is given. Comparison of various characteristics indicates that maximal difference for samples of diamonds from different sources and minimal diversity for different samples from one source have average values of absorption coefficient and maximum positions of B2 absorption band. The revealed parameters are proposed to be used during comparative analysis of diamonds of different kimberlite pipes, determination of the initial source of placer diamonds, forecasting of new sources.