The invention relates to an illumination system comprising a radiation source and a fluorescent material comprising at least one phosphor capable of absorbing a portion of the light emitted by the radiation source and emitting light of a wavelength different from that of the absorbed light; wherein said at least one phosphor is a green-emitting cerium-activated lutetium-aluminum-garnet of general formula (Lu1-x-y-a-bYxGdy)3(Al1-zGaz)5O12:CeaPrb wherein 0