Left: J − H versus H − K colour diagram. The dot points represent all objects selected with the mid-infrared selection criteria. All the new and known Magellanic and Galactic bulge RCB stars are represented; their symbols are identical to those in Fig. 1. The dotted curve corresponds to the combination of black bodies consisting of a 5500 K star and a 1000 K dust shell in various proportions ranging from all “star” to all “shell” (from Feast 1997). The straight lines delimit the near-infrared selection area (see Eqs. (1) and (2)). The line on the right side represents the reddening vector of Rieke & Lebofsky (1985). Also shown are the expected positions (lines in the bottom-left side) of common dwarf (green) and giant (black) stars from Bessell & Brett (1988). Right: CMD absolute magnitude M_K versus K −  [5.8]  of all objects that passed the two infrared selection criteria.