Various effect pigments like pearlescents and metal pigments made of gold or copper-zinc alloys have long been used to decorate surfaces in a wide variety of applications. Colours in metallic elements and their alloys can be explained using band theory whereas (interference) colours in pearlescent pigments are formed by thin layers of higher refractive index deposited on semitransparent substrates with platelet-like morphology [3]. With regards to the physics of Au-Ag-Cu alloys and their object surfaces, particle properties such as scattering at pigment edges and particle orientation must be taken into account when processing effect pigments in coatings, printing and plastics ...