A rolling cone bit and a cutting insert for a rolling cone are disclosed. The insert includes an undulating cutting surface including a peak, and blades radiating therefrom. The cutting insert may include an ultrahard layer of diamond or other superabrasive material, wherein the outer cutting surface of the layer includes contours that generally correspond to the contours of the interface surface that is between the ultrahard layer and the substrate so as to reduce residual stresses and lessen the likelihood of spalling or delamination of the ultrahard material. The blades radiate from a central peak and may include a sharper and/or higher leading edge as compared to a trailing edge. Valleys between the blades may differ in depth, and the cutting surface may have an undulating perimeter.