High-quality (uniform in size and morphology (σ = 3−5%), high crystallinity, high QY (40−85%), sharp and narrow absorption onsets and PL peaks (fwhm = 27−33 nm)) violet- to red-emitting ZnSe/CdSe core/shell nanocrystals have been prepared by the deposition of Cd/Se precursors (CdO and elemental Se, respectively) into a diluted crude ZnSe nanocrystals reaction solution.