User blog comment:Merlaa/Why "The Diamond of the Day"?/@comment-5734522-20121221151231/@comment-5734522-20121224053019

What I mean is, there will be a magic reveal to everyone, thus they will recognize merlin's value, they will look up to him, Arthur will understand he is more than a servant and a friend. So, he goes from coal to diamond.

I don't know if there is a sacrifice, perhaps it is.