Observed UCD candidates on a zoomed Gaia M_G - G – J and G – G_RP diagrams: UCDs are coloured by their obtained spectral type, as explained in Sect. 3. The two circled UCDs have peculiar colours (see text). Subdwarfs candidates are represented by crosses (see Sect. 4.1). Peculiar objects are represented by triangles (Sect. 4.2). The UCDs with common parallaxes and proper motions with another system are represented by diamonds (see Sect. 4.3) and those in (potentially) unresolved binary systems by squares (Sect. 4.4). The grey points are the sources from the Gaia Catalogue of Nearby Stars, with a RUWE < 1.4. The insets illustrate the locus of our sample on entire Gaia Catalogue of Nearby stars colour-absolute magnitude diagrams.