Are there any notable examples where (for example) an archaeological dig turned up one half of a pair of items where the other half of the pair was already in a museum, having never been lost/buried (maybe having been preserved in a royal collection or some such?
Ditto for things that are sets, rather than pairs - I’m looking for examples where a long-lost item was found, completing a non-lost, but long-incomplete set.
Maybe not exactly what you’re looking for, but there’s a painting at the Museum of Fine Arts in Boston that apparently was cut out of a larger painting, and was recently reunited with one of the missing top parts. It seems that in an earlier age, dealers would take a large painting with several scenes in it, and divvy it up into smaller and more marketable paintings.
I wish I could tell you the name of the painting at the MFA, but I’ve just spent the last half hour searching in vain for it. One of the rare times where Google has utterly failed me.
I just recently acquired the Hand of Vecna after toting the Eye around for about a decade.
Here is a slightly better example, also involving the MFA:
Did you find the Triangle of Zinthar?