The Formal Ensemble
The peaked lapel is the commander-in-chief of the pack, the elder brother of lapels, and it shows you mean business. The moniker comes from the style of the lapel as it falls against the collar. It accentuates the upper part of the body prominently, and thus visually enhances the physique of the suit-wearer.
Peaked lapels should never be too narrow. They should come up to two-thirds across the shoulder, unlike notch lapels that usually just reach to under half the shoulder width. Certain labels such as Tom Ford tend toward a broader lapel to add flamboyance to the suit. Lapo Elkann, style savant and all-round cool guy, wears peak lapels as broad as his shoulders.
Where three-button suits were standard for formal suits, the two-button is de rigueur today. It offers the appearance of a longer torso against the pant. One should also pay attention to the shoulder of a suit, which helps to define it more strongly with the chest piece. Giorgio Armani's master tailor Mario Vergani points out that the con rollino, or the roll, where the arm hole is cut slightly smaller than the shoulder so it forms a slight protruding roll when stitched, is a more formal look.