We demonstrate a simple and technologically viable process of nanodiamond deaggregation by ozone/oxygen gas mixture treatment of detonation nanodiamonds (DNDs) followed by horn sonication in alkaline water to obtain single digit DND colloids without milling. The dried deaggregated DNDs demonstrate outstanding redispersibility in water. Characterization of the deaggregated DND shows that the horn sonication process in water leads to efficient hydrolysis of surface anhydrides created by ozone oxidation to carboxylic acid groups, thus increasing hydrophilicity of the DND surface.