Peer gems appeared first in Ultima III (before, there were other ways to look at the map; see Trivia below). They could only be bought at the illegal guild shops and were quite expensive. This didn't change in Ultima IV, although in Ultima V monsters could often be found carrying them. By Ultima VI, any tool shop sold them. After the time of the False Prophet, they vanished without a trace.
- The gem given by Lord British at the beginning of Forge of Virtue in a way also works like a peer gem, only it showed one special place.
- The spell "Peer" fulfilled the same function as these gems.