As for the item icon, I notice a little difference between the Philosophy ones and the Mythology ones. Perhaps the "number of blue stripes" would indicate the "either the subject or importance" of what would be on the tomestone [Philosophy ones have 1 stripe and Mythology ones have 2 stripes].

I also note that the way the icon looks like, it's possible for one to have up to 4 stripes, so there may two more varieties in the future, more if they come out with ones with different color stripes on them.