'Diadems' in the Bible

And another sign was seen in the heaven: and behold, a great red dragon, having seven heads and ten horns, and on his heads seven diadems;

And I stood upon the sand of the sea; and I saw a beast rising out of the sea, having ten horns and seven heads, and upon its horns ten diadems, and upon its heads names of blasphemy.

And his eyes are a flame of fire, and upon his head many diadems, having a name written which no one knows but himself;