A dual referent approach to colour theory maintains that colour names have two intended, equally legitimate referents. For example, one might argue that ‘red’ refers both to red appearances or qualia, and also to the way red objects reflect light, the spectral surface reflectance properties of red things. I argue that normal cases of perceptual relativity can be used to support a dual referent approach, yielding an understanding of colour whose natural extension includes abnormal cases of perceptual relativity. This contrasts with Peacocke's multi-referent view, according to which such abnormal cases force us to introduce a wholly distinct kind of colour experience. I also argue that the two uses of colour names, arising from their two referents, have different extensions, even in normal perceptual circumstances, a consequence which conflicts with the heart of Rosenthal's dual referent view.