The invention relates to a conversion material, in particular for a white or colored light source comprising a semiconductor light source as primary light source, comprising a matrix glass that, as bulk material, for a thickness d of about 1 mm, has a pure transmission τi of greater than 80% in the wavelength region from 350 to 800 nm and in the region in which the primary light source emits light, wherein the sum of transmission and reflection of the sintered matrix glass without luminophore is at least greater than 80% in the spectral region from 350 nm to 800 nm and in the spectral region in which the primary light source emits light.