  Spherulites are birefringent sturctures with spherical symmetry, which are
typically observed in crystallized polymers. We compute the band structure of
opals made of close-packed assemblies of highly birefringent spherulites. We
demonstrate that spherulitic birefringence of constituent spheres does not
affect the symmetries of an opal, and yet significantly affects the dispersion
of eigenmodes, leading to new pseudogaps in sections of the band structure, and
consequently enhanced reflectivity.
