Pseudo-colour maps of 47 Tuc (upper left panel) and NGC 3201 (upper right panel) from the only published data in M23 and M19, respectively. Stars are colour-coded according to their metallicity. In the lower panels, aqua is used for all stars that have [Fe/H] values within ±0.10 dex (the internal error associated with the metallicity) of the average metallicity of FG stars in each cluster, whereas those that lie outside this range are marked in black.