File:Denmark crown 1596.jpg

The crown of King Christian IV of Denmark, now located in Rosenborg Castle, Copenhagen. This was the Crown of Denmark at the time Shakespeare was writing Hamlet as we now have it.

From Wikipedia:

http://en.wikipedia.org/wiki/Danish_Crown_Regalia

From that page:

... At the center of each of the larger points is an enameled allegorical figure of one of the king's ruling functions and virtues. The three points above the king's forehead and behind each of his ears bears a "pelican in her piety." The point on the right of the king's forehead bears a representation of Fortitude riding a lion, while that on the left bears the image of Justice as a woman holding a sword and a pair of scales. The point above the back of the king's neck bears the traditional image of Charity as a mother suckling her child. ...

The pelican, lion, Justice, sword, the scales, and Charity are all mentioned, or clearly referenced, in the play dialogue. Such symbols and concepts are hardly unique, but the number is intriguing. It is entirely possible the concepts and symbols could appear in the play without the author having detailed knowledge of the Crown, because of cultural commonality.