[Fe/H] ratios as a function of effective temperature for stars analysed in NGC 1851 (upper panel), M 4 (middle panel), and M 5 (lower panel), both from Carretta et al. (2009a,b). The filled red circles indicate stars with GIRAFFE spectra, the blue filled squares stars with UVES spectra. Error bars in the left and right side of the panels refer respectively to our GIRAFFE and UVES data and indicate star-to-star errors.