Abstract <p>This paper discusses the optical properties of multicenter GSAG:Ce crystals grown by vertically directed crystallization and polycrystalline samples prepared by solid-state reactions. The absorption and luminescence bands of Ce³⁺ ions in the GSAG:Ce crystal are formed by seven different activator centers. Almost half of the activator ions occupy dodecahedral sites surrounded by six octahedra occupied by Sc³⁺ ions. The second part of Ce³⁺ ions is surrounded by octahedra with various combinations of Sc³⁺ ions and Al³⁺ ions, as well as only Al³⁺ ions. The shape of the luminescence band (∼18 700 cm^–1) of Ce³⁺ ions of GSAG:Ce crystals containing from 0.5 to 2.5 at % of the activator is stably preserved, and the emission intensity increases with increasing concentration of Ce³⁺.</p>