The structure and optical properties of artificial opal thin films, which were synthesized from silica spheres by a modified self-assembly protocol, in the absence and under the applied magnetic field were studied. The surface characterization showed a homogeneous well-ordered face centered cubic structure of silica balls at average size 305 +/- 5 nm. The reflection measurements showed the main reflection plane (1 1 1) besides a minor secondary (2 0 0) plane. The applied field (up to 1000 Oe) induced a systematical splitting of several lines which showed an increase in intensity according to the increase in applied field and thickness of substrate coating MnO(2) layer.