Conservators and restorers need to be concerned with pigment identification for at least four reasons. 1. To decide whether (a) all restoration should be carried out with the original pigment and not with alternatives of similar hue; this is important since some alternatives might be liable to react with contiguous pigments with deleterious visual effects or (b) restoration with a different pigment might be desirable owing to instability of the original one or because it is more desirable to restore with carefully documented and easily identifiable nonoriginal pigment, possibly modern.