This handbook is a breakthrough in the understanding of the large number of spectral lines in diamond. Data on more than 2000 lines and bands are presented in 200 tables, including many unpublished results. In order to meet the interest in the understanding of the spectra, structure assignments for 80 % of the lines are given, of which 15 % only were published before. The majority of the structures for the 300 centers is explained in most cases for the first time.