Diamond-shaped faces are very angular. There is usually a short forehead, and the face is wider at the temples than at the forehead or jawline. A diamond-shaped face appears to have sharp angles, in contrast with the round face type.
Your aim is probably to draw attention away from the width of the face at the temples, and to create a softer, less angular impression
How to achieve it
You definitely need to avoid the extremes of very high arches and angles or horizontal line shapes. Curved brows with low arches, or round brows, are the best way to achieve the optimum effect.
A curved eyebrow shape with a low arch may be ideal for you. It will complement your face shape, help to neutralize the angular look of your face, and reduce the apparent size of the widest part of your head.
A simple rounded look – ‘soft-angled’ – which is ideal for oval face types, may work for you too.