As they Say, "The Fella Wears His Own Hat"

R.A. Foakes explores a nice point of millinery in discussing Shakespeare's play about the King who would and would not surrender the attributes of his office:

Some have thought that when Lear offers a coronet to Cornwall and Albany at 1.1.140, he takes one from his own head, but Shakespeare and his audience well knew the difference between crowns and coronets: crowns typically had raised sides, were "archée," that is, had between four and eight arches over the circlet, and were topped with an emblem sym

bolic of the power belonging to kings.  Coronets (the word is a diminutive of 'crown') were circlets worn by princes and dukes.  It makes dramatic sense if Lear wears such a crown at the beginning of the play, and gives a coronet intended for Cordelia to Cornwall and Albany; he acts imperiously all through the scene, and if he continues to wear a crown until his exist this would highlight visually the irony of his actions in giving away his power yet seeking to retain his royal prerogatives, 'The name, and all th'addition to a king'.(1.1.137).

--R. A. Foakes, "Introduction" 14-15 to King Lear, The Arden Shakespearem (3d Ser.)  (2004).  

*I tried to find a nice picture of a "coronet," but they kept sending me to the 1966 Dodge, or the ladies' magazine, or to a "cornet," which isn't the same thing at all.