Achievement Diary Cape gets cut following the RS gold completion of the quests, making the cut version more difficult to find. Similar to Quest Point Cape, this item is cut off whenever a new quest comes out. It only gets cut when all quests in the game have been completed. Therefore, each new task must be completed as well.
The untrimmed and trimmed versions of this cape offer an additional 9 points to any defensive stat and a +4 bonus to Prayer ability, making it the best slot-untrimmed capes to use for Prayer. Achievement Diary Cape also has 10 daily teleport fees to anyone who is an Achievement Diary Master, which makes it an ideal transport item.
While some of the accomplishments are located at Draynor Village, Varrock, Lumbridge and other free to play areas, Achievement Diaries are not accessible to non-members. So even if you take the correct steps, it won't give the appropriate rewards to buy OSRS GP the player who is f2p. Although there have been numerous rumors of creating new Diaries specifically for players who are free, there is no evidence from Jagex.