This is the kind of thing I would likely go for if I had unlimited funds. It’s rare and unique, tells a story, and just makes you wonder about who originally gave it to whom.
This betrothal ring is estimated to be from the 7th or 8th century. Offered by Berganza, they explain, “Set centrally with a flat square plaque engraved with two crowned full-length figures flanking a cross, all within a dotted border, and on a smoothly conforming D-shapeshank. Tested yellow gold, circa 7th-8th century AD, accompanied by an Oxford Labs X-ray fluorescence report stating the composition of the metal.
This is an extremely rare example of one of the earliest types of engagement rings. A highly similar ring can be found in the collection of the Victoria and Albert Museum (M.184-1937).”
This is selling for £34,000/€38,420/$42,160/CHF40,800/HK$327,760.