Reddened [J – H]/[H – K] color-color diagram of the reference Group 1. All sources in the figure were reddened by A_v = 2.4 mag along the reddening lines. The A_v value represents the derived median value of background/Class III objects with their dust column density <1.2 × 10²¹/cm² in the R CrA region. A black arrow shows the reddening vector of A_v = 2.4 mag. Lines and markers in the figure are the same as in Fig. 6.