The density differential between the overflow and underflow streams is one of the critical measurable parameters in the operation of dense medium cyclones. Our investigation of the application of a magnetic cyclone to dense medium separation showed that by a judicious positioning of a solenoid magnet along the axis of the cyclone, and by adjusting the strength of the magnetic field, it is possible to control the density differential in the cyclone. It is also possible to influence the cut-point density and the sharpness of the Tromp curve and the selectivity of separation. Typically, it was possible to vary the density differential in a wide range from −0.1 to 0.8 g/cm³. The cut-point density was controlled between 2.8 and 3.2 g/cm³ for 270D ferrosilicon, at a feed density of 2.35 g/cm³, and between 3.1 and 3.4 g/cm³ for Cyclone 60, at a feed density of 2.45 g/cm³. The Ep of separation was observed to decrease from 0.05 to 0.01 by the application of the magnetic field, accompanied by reduced cut-point density.