Imitation de la pierre de Slocum

locum stone (John L. Slocum, 1920-1988) is a fairly convincing opal imitation, featuring iridescence due not to diffraction by a two- or three-dimensional grating, but to interference colors from thin films of aluminum oxyde within a silica matrix. Here, we present a lower-grade Slocum stone imitation made from a polymer matrix with interferential film flakes. This type of manufacturing can be considered obsolete compared with diffraction grating-based imitations, but remains a textbook case.