Colour absolute magnitude diagram (CaMD) of stars that have photometric metallicities from MS23 (Pristine Gaia synthetic and Pristine DR1 catalogues) and A23 Table 2 giants catalogue less than −2.0 dex. Duplicates between the three catalogues are shown as purple star symbols. The selection is justified by using 13 Gyr −2.2 [M/H] PARSEC isochrone shifted by ±0.6 mag in BP₀ − RP₀ and ±0.6 mag in M_G. The blue polygon is the selection area for VMP stars analysed in this paper. The number of stars selected in each catalogue is shown in braces in their legend labels.