Evolutionary tracks of AGB stars from the GRAMS models. Carbon-rich AGB stars (blue) occupy a narrow range in color space. Oxygen-rich sources (yellow) have a wider spread in color. The points line up roughly in rows and/or columns, corresponding to sets of models with the same ﹩{T}_{\mathrm{eff}}﹩, ﹩{R}_{\mathrm{in}}﹩, and luminosity, but increasing mass-loss rate. As the mass-loss increases, the AGB stars appear brighter and then redder in the CMDs. Only models with a stellar effective temperature of ﹩{T}_{\mathrm{eff}}=2100\mbox{--}4700\,{\rm{K}}﹩, a dust shell inner radius of ﹩{R}_{\mathrm{in}}=3﹩ or 7 ﹩{R}_{\mathrm{star}}﹩, and log(g) = −0.5 are shown. The models are set at a distance of 50 kpc. These CMDs can be directly compared with the observed sample in Figures 3(B) and (F).