Diamond faces are widest at the cheekbones, with a narrower forehead and chin. Frames that add width at the brow — like cat-eye or oval shapes — help soften the cheekbones and bring balance to the face. Rimless or lightweight frames can also work well by keeping the focus on your features rather than the frame itself. Avoid narrow, angular frames, which can emphasize the cheekbones too much.
Source: https://migafas.com/collections/diamond-face