Abstract: There is described a process for the spectral sensitization of photographic silver halide emulsions which comprises forming and chemically sensitizing silver halide crystals in a colloid dispersion medium, the process being characterized in that it comprises forming a shell of silver halide on the chemically sensitized crystals by simultaneously adding to the dispersion an aqueous solution of a water soluble halide or pseudo-halide, an aqueous solution of silver nitrate and a J-band aggregating spectral sensitizing dye in an aqueous medium, the said simultaneous additions being continued for sufficient time to form a shell of silver halide or pseudo-halide on the said chemically sensitized silver halide crystals which is up to 15 mole percent of the total silver halide or pseudo-halide of the fully grown crystals.