If it doesn't have a coating it should be easy.
I would buy a single piece and experiment to see which compound will match the luster. Probably a mild jeweler's rouge, toothpaste, or a cape cod cloth would work. But I wouldn't want to test on my original pieces.
Good luck and let us know how it turns out.
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Retired 2016 BMW 550i xDrive MSport | 2013 BMW 550i xDrive MSport | 2012 BMW 535i xDrive | 1988 BMW 325ic | 1984 BMW 318i
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