The optical properties of Co 2 + -doped BaMgAl 1 0 O 1 7 (BAM) and BaMgAl 1 0 O 1 7 :Eu (BAM:Eu) are elucidated with emphasis on reflection, (V)UV excitation and luminescence spectra. Doping of BAM with Co 2 + yields a powder with a blue body color equal to that of CoAl 2 O 4 . Co 2 + is incorporated into the spinel blocks of BAM, which are spaced by Ba-O layers hosting the activator Eu 2 + . By means of reflection spectra it is shown that the local environment of Co 2 + is equal to that in CoAl 2 O 4 , which is responsible for the identical body color.The intrinsic pigmentation of BAM:Eu by Co 2 + yields a phosphor with an improved color point due to the self-absorption of the low-energy tail of the 4f-5d emission band of Eu 2 + . Moreover, the presence of Co 2 + in the host lattice of BAM results in resonant afterglow behavior. Only under photoexcitation at the band gap of BAM:Eu afterglow is observed.