I never realized the importance of color when it comes to wearing a zucchetto. Now I understand why the pope always has on a white one and the men standing with him are wearing a bright red.
My husband grew up in the Catholic church and we have been to several masses and ceremonies in his church. I don't remember any of the priests wearing a zucchetto.
It seems like it might be appropriate to wear a black zucchetto for a funeral, but since I have never seen this done.