a) Difference between microlensing colours and the spectroscopic colours versus spectroscopic T_eff. b) Difference between the absolute I magnitudes from microlensing techniques and from spectroscopy versus stellar mass (derived from spectroscopy). Error bars represent the uncertainties in the spectroscopic values. The microlensing values used in the plots are based on the assumption that the bulge red clump has (V − I)₀ = 1.06 and M_I =  −0.12. Stars with T_eff > 5500 K are marked by filled circles, otherwise by open circles.