Board Thread:Skyrim/@comment-121.73.26.87-20160131104227/@comment-6881629-20160131110940

It probably disappears, either completely removed from the game or just hidden in the inventory of whoever you give it to. Like the quests bugs list and the items page says the crown can only be kept by reverse pickpocketing it during the quest or maybe using a mannequin to make a duplicate (if that still works). On a PC the crown could be spawned with commands or there are mods for craftable versions (if you do want the crown).