A blazer is the fastest way to make an outfit look decided. This edit runs from sharp single-breasted tailoring for the office through to cropped, oversized and embellished styles built for evening. Shoulder construction is what separates them: a structured shoulder holds a line and reads formal, while a soft or dropped shoulder relaxes the whole piece. Worn open over a dress a blazer adds structure without covering it; buttoned with trousers it becomes a suit. Fabrics run from tailoring cloth and crepe through to satin, tweed, denim, faux leather and sequin. Size a blazer on the shoulder rather than the bust — a shoulder seam that sits past the joint is the one thing that can't be adjusted later.