The original color of the diamonds in the as-received state was fancy brownish yellow (Fig. 1a). The diamond treated with LPHT annealing at temperature 1800 "C changed its color to fancy yellow (Fig. 1b). The diamonds treated with irradiation followed by LPHT annealing at temperature 1800 "C turned fancy orangey yellow (Fig. 1c). Fluorescence images of these diamonds excited with 360 nm UV light are shown in Fig. 1d, e,f correspondingly. All as-received diamonds revealed bluish green fluorescence. The fluorescence of the diamond treated with sole LPHT annealing became greener. The fluorescence of the diamonds processed with irradiation and LPHT annealing turned almost blue with a faint trace of green and pink colors, Diamondview images of the LPl-lT—treated diamonds revealed strong greenish yellow fluorescence, the yellow component being stronger after lrr + LPHT treatment (Fig. lg, h, k).