A white-light emitting lighting device comprising one or more light emitting light sources (preferably solid state semiconductor light emitting diodes) that emit off-white light during operation, wherein the off-white light includes a spectral output including at least one spectral component in a first spectral region from about 360 nm to about 475 nm, at least one spectral component in a second spectral region from about 475 nm to about 575 nm, and at least one deficiency in at least one other spectral region, and an optical component that is positioned to receive at least a portion of the off-white light generated by the one or more light sources, the optical component comprising an optical material for converting at least a portion of the off-white light to one or more predetermined wavelengths, at least one of which has a wavelength in at least one deficient spectral region, such that light emitted by the lighting device comprises white light, wherein the optical material comprises quantum confined semiconductor nanoparticles. Also disclosed is an optical component, lighting fixture, a cover plate for a lighting fixture, and methods.