Gaia CAMD for different samples in this paper: (top left) sample 1, (top right) differential 1–3 sample, (bottom left) differential 3–4 sample, and (bottom right) final sample. All panels include the solar metallicity Geneva-Padova 1.0 Ma MS isochrone of Maíz Apellániz (2013) and the 1.0 and 2.0 Ma PMS isochrones of Baraffe et al. (2015) with the two extinctions that span the range measured for Stock 18, E(4405 − 5495) of 0.55 and 0.81 mag, in both cases with R₅₄₉₅ = 3.38. Empty squares mark the initial masses in the MS isochrone and the PMS isochrones extend to 1.4 M_⊙. In the first three panels each sample member is colored according to σ_G from Maíz Apellániz et al. (2023). In the bottom left panel typical color error bars as a function of M_G are shown. In the bottom right panel the coloring scheme is the same as in Fig. 9 and reflects the probability of belonging to the cluster. A distance of 2.91 kpc is assumed for all stars (distance modulus of 12.32 mag).