J − H vs. H − K diagrams using the 2MASS magnitudes of all objects listed in the ASAS-3 ACVS1.1 variable stars catalogue (black dots). The red lines show the selection criteria used in nalysis A. The blue points correspond to the RCB stars that were previously known, the red points to the 23 newly discovered RCB stars. The green lines represent the selection box used to find new DY Per stars. The green points correspond to the two new DY Per stars.