Development of efficient and cost-effective mass-production techniques for size reduction of high-pressure, high-temperature (HPHT) diamonds with sizes from tens to hundreds of micrometers remains one of the primary goals towards commercial production of fluorescent submicron and nanodiamond (fND). fNDs offer great advantages for many applications, especially in labelling, tracing, and biomedical imaging, owing to their brightness, exceptional photostability, mechanical robustness and intrinsic biocompatibility. This study proposes a novel processing method utilizing explosive fragmentation that can potentially be used for the fabrication of submicron to nanoscale size fluorescent diamond particles. In the proposed method, synthetic HPHT 20 µm and 150 µm microcystalline diamond particles containing color centers are rapidly fragmented in conditions of high explosive detonation. X-ray diffraction and Raman spectroscopy show that the detonation fragmented diamond particles consist of good quality submicron diamonds of ~420-800 nm in size, while fluorescence spectroscopy shows photoluminescence spectra with noticeable changes for large (150 µm) starting microcrystalline diamond particles, and no significant changes in photoluminescence properties for smaller (20 µm) starting microcrystalline diamond particles. The proposed detonation method shows potential as an efficient, cost effective, and industrially scalable alternative to milling for the fragmentation of fluorescent diamond microcrystals into submicron-to-nano-size domain.