In this work, the role of elaboration parameters (i.e. chemical composition and heat treatments) of Cr:YAG ceramics on their microstructural, optical and laser properties was investigated. Transparent ceramics were manufactured by solid-state reactive sintering under vacuum. Spatial distribution of sintering additives and luminescent dopant (Ca, Mg, Cr 3+ and Cr 4+) has been determined by coupling TEM, LSFI and NanoSIMS complementary techniques. Ca and Mg were found to segregate at grain boundaries whereas Cr appears to be homogenously distributed in Cr:YAG ceramics. Samples were used as saturable absorber of Nd:YAG laser and exhibited good optical properties, i.e. saturation fluence of 4500 J.m-2 , laser pulse energy of 38.8 mJ with pulse duration of 45 ns.