Abstract. A previously calculated universal pattern (Berry M V 2002 New J. Phys. 4 66) describes colours near an isolated phase singularity (diffraction zero), generated with white light and visible when the dark light of the singularity is scaled to isoluminance. Here the pattern is illustrated in several different situations: near the zeros of random and regular superpositions of plane waves, and near the zeros inside and outside the diffraction pattern decorating the geometrical cusp catastrophe. The universal colours emerge in miniature, close to the zeros, when an initially achromatic diffraction pattern is perturbed by switching on an asymptotic `chromaticity parameter', that can be chosen in several different ways.

Received 2 September 2002, in final form 24 September 2002
Published 21 October 2002