Cluster CMD for all the Gaia EDR3 bona fide members of Westerlund 1 and spectroscopic members from Clark et al. (2020) not selected by the algorithm. Diamonds represent the most luminous hyper- or supergiants (according to colour, blue, yellow – including the LBV Wd1-W243 – and red). Triangles are luminous B-type supergiants (those classified as Ia). Green triangles have mid-B types, while turquoise triangles have early-B types. The bulk of OB members is represented by circles. The larger blue circles represent the astrometric members, while the smaller brown circles are stars in Clark et al. (2020) not selected by the algorithm. The orange circles represent the candidate high-reddening sample. The red squares are objects that present much redder infrared colour than typical, (J − K_S) > 2.2.