Vintage jewellery adds retro class to a look. Especially loud or ornate options easily become the centrepiece and uplift any standard ensemble. Older silver pieces coordinate just as well with outfits now as they did when they were first made.
A 1940s rhinestone bridal cuff makes a glittering addition to any dress and meets the "something old" criteria as does a 1950s marcasite floral brooch. Even just one or two pieces of vintage jewellery transforms the feel of an outfit.