The optical properties of interplanetary grains depend not only on chemical composition, size, and shape but also on lattice defects. It is argued that practically all sources for the zodiacal dust cloud yield grains with highly disturbed crystal structure. Healing of these defects can occur when the grains are heated in the vicinity of the sun (≤0.1 AU) and various orbits are considered, on which annealed grains with nearly perfect crystal structure can return to larger heliocentric distances to reveal the sharp optical features of cold well-ordered crystals. However, we do not find any processes, which produce healed particles of sufficient number to affect the properties of the general zodiacal cloud. Therefore, the optical properties of interplanetary grains are determined by a high degree of lattice perturbation.