Audrey Hepburn is revered to this day as a style icon, and with good reason. Her looks throughout the decades have been emulated and idolized and many (if not most) are still wearable today. When she married actor Mel Ferrer in 1954, he presented her with three stacking bands, one a white gold eternity set with 1.5 carats of baguettes, and faceted rose and yellow gold rings she could wear with it, or not, as she chose. These were untraditional choices for the time, when a solitaire (often complimented on either side with baguettes) was seen as the more popular choice. The stacking trend is huge today but in the 50s, not so much. As with much else style related, Hepburn was ahead of her time (or at least her then-fiance realized she was).
The photo below is the Daily Mail’s interpretation of the rings, with an estimate of today’s value. Provenance would, of course, make them much more valuable.