'Diadems' in the Bible

Then another sign [of warning] was seen in heaven: behold, a great fiery red dragon (Satan) with seven heads and ten horns, and on his heads were seven royal crowns (diadems).

And the dragon (Satan) stood on the sandy shore of the sea.Then I saw a [vicious] beast coming up out of the sea with ten horns and seven heads, and on his horns were ten royal crowns (diadems), and on his heads were blasphemous names.

His eyes are a flame of fire, and on His head are many royal crowns; and He has a name inscribed [on Him] which no one knows or understands except Himself.