Geochemical and isotopic data from the manuscript "Assessment of natural reference materials for U-Pb geochronology of grossular-andradite garnet" published in Geostandards and Geoanalytical Research. Table 1 is a summary of major and trace element geochemical characteristics of the three reference materials investigated in this study. Table 2 and Table 3 show the results of ID-TIMS analyses performed on each of the reference materials.