Magnetically tunable photonic structures are prepared in alkanol solutions by using silica-modified superparamagnetic Fe3O4 colloids as building blocks. Repulsive electrostatic and solvation forces and magnetically induced attractive forces contribute to the ordering of the Fe3O4@SiO2 colloids. The ability to form tunable photonic structures in nonaqueous solutions allows the fabrication of field-responsive polymer composite films for potential applications as displays and sensors.