that are layer-by-layer coated with polyelectrolyte or polyelectrolyte/gold nanoparticle multilayers permit control over the peak position of the optical stop band of the assemblies through variation of the coating thickness and composition. The crystalline arrays made of polyelectrolyte multilayer-coated colloids can also be used for infiltration of gold nanoparticles. (F. Caruso et al., August 16, Adv. Mater. 2002, 14, 1160-1164)