The Stöber process is revisited using vinyltriethoxysilane as the precursor, where a kinetics-controlled condensation of vinylsilanols, free from external fluorogens, unprecedentedly produces hydrophilic diamond-structured organosilica nanocrystals (ca. 2-6 nm) with finely tunable fluorescence (460-625 nm). The key to the synthesis lies in a slow successful condensation of vinylsilanols triggered and guided by the π-π stacking interaction of vinyl groups.