Colour-colour diagrams for 508 stars from the miniJPAS survey classified as FGK stars (4 000 ≤ T_eff ≤ 7 000 K), colour-coded according to their derived effective temperature. The comparison sample – from the MILES, STELIB, and ELODIE libraries – is shown in grey, and dwarfs and giants are represented by crosses and squares, respectively. The solid lines show the best separation between the two groups according to the SVM solutions.