1. A process for increasing the fastness to light, the fluorescence polarisation and fluorescence quantum yield of cyanine dyes, which process comprises stabilising cyanine dyes with the aid of micellar structures of a) surfactants and/or b) surfactant crown ether complexes of monovalent of divalent transition metal cations, or c) mixtures of surfactants, in each case in combination with non-surfactant, nitrogen-containing or nitrogen- and oxygen-containing 16- to 18-membered crown ether complexes of monovalent or divalent transition metal cations.