Disclosed is an ink composition suitable for ink jet printing comprising a luminescent compound, a solvent, and an energy active compound, and optionally a non-luminescent colorant. The energy active compound, when exposed to energy, generates one or more active species that can react with the luminescent compound to alter one or more of the characteristics of the luminescent compound. The luminescent compound can be colored or colorless. Also disclosed is a method for marking substrates comprising providing a mark comprising a luminescent compound and an energy active compound. Further disclosed is a jet ink composition suitable for printing on substrates authentication or security marks which can be rendered unreadable. The luminescence of the mark is quenched and the visible color is changed when irradiated with a light.