Compare your forehead width, cheekbone width, and jaw width. If your cheekbones are clearly the widest point and both your forehead and jaw are noticeably narrower, you have a diamond face.
The goal is adding width at the forehead and jaw to balance dramatically prominent cheekbones.
Frames that add visual width to the forehead and soften the narrow chin work best. Avoid frames that sit wide at the cheekbones.
Cat-eye frames are the #1 pick for diamond faces — they add width exactly where it's needed at the narrow forehead.