In this article, we discuss the crystal chemistry and luminescence properties of Ce3+ activated silicate garnets. Our results indicate that the two previously reported end members of this family, Lu2CaMg2Si3O12 and Ca3Sc2Si3O12, form a complete solid solution, and Sc3+ primarily substitutes for Mg2+ in the octahedral sites with charge compensation by Ca2+ substitution in the dodecahedral sites. Within this solid solution, there is a continuous shift in the lowest energy Ce3+ 4f -> 5d excitation band and the Ce3+ 5d -> 4f emission band toward higher energy as the composition is varied between Lu2CaMg2Si3O12 and Ca3Sc2Si3O12. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3380854] All rights reserved.