Hi Kuan,
im not entirely sure what a "One Ring" is, but if its a piece of jewellery, and its a surprise, then this might work. Does your wife wear a ring at all, even like costume/occasional pieces? if so, and she wouldnt miss it for a day, grab it and take it to a nearby gemstore. or if theres a jewellery maker/artist near you, even better. they will have a ring bar kinda like a butchers steel - a tapering rod that has graduated ring sizes on it. the ring will slide up to the corresponding size.

if its something from Tolkien your looking for, then may the Farce be with you

Tony

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