A device was developed to measure the rheological properties of coarse suspensions exhibiting zone settling properties. The device is an elongated double gap cup and bob arrangement that can be attached to most rotational viscometers. It was tested on magnetite aqueous suspensions which are used by industry in beneficiation processes as dense media. In the design, the bob is positioned in an elongated cup so that it is completely within the constant density zone of the settling suspension for the duration of the measurement. Other design features include vertical grooves in the shearing surfaces of the cup and bob to reduce wall slip errors, and narrow gap sizes to lessen non‐Newtonian shear rate effects. Tests were conducted to confirm theoretical aspects of the design and to establish measurement constraints such as the maximum shear rate at which laminar flow is maintained. Finally, measurements obtained using the new device are compared to those acquired using a conventional fixture.