The parts of the page that must be older from more credible editors clearly indicate a "diadem" is something specific that is unique from other types of metal headwear things, but then people messed up the page to expand the meaning, and to be racist fools who won't leave it be as an Eastern thing of any kind. (Literally, the groups that must have been added in directly hype up the favorite ethnicities of white supremacists, black supremacists, and Middle Eastern supremacists. And, at least one of the examples used by white supremacists is not a diadem (from what "diadem" seems to mean), but a normal European crown, so WTF?)