A method of manufacturing a prepreg composition includes disposing a plurality of core/shell quantum dots on or in a resin matrix of the prepreg composition. The quantum dots may include an inner core that when excited by light of a first wavelength emits a detectable luminescent signal, and an outer shell that blocks light of the first wavelength from reaching the inner core when the outer shell is intact. A method of determining the suitability of a pre-impregnated composite fiber material for incorporation into a composite structure and a method of detecting damage to a prepreg composition due to ultraviolet radiation exposure utilizing the core/shell quantum dots are provided.