The stone he put in its place looked almost exactly like Jon's stone, but it wasn't. It was the Stone of Plenty.
Even though the rules governing wishes made upon the Stone of Plenty were exactly the same as those on Jon's other stone - aside from the fact that the Stone of Plenty's wishes could be reversed with another wish - the methods for granting such wishes was quite different.
Whenever the Stone's bearer would make a wish on the Stone of Plenty, instead of granting their desire immediately the Stone would create a few dozen little sweets out of thin air. While they looked and tasted much like jelly beans, when eaten each of these sweets would instantly grant any who consume them a copy of the wish from which they were created, just as if that person was the target of the wish.
Unfortunately with so many multi-coloured beans spawned each time, wishing on the Stone of Plenty would always prove a quite wasteful endeavour. Perhaps Jon would have what it takes to keep the produce from the Stone of Plenty out of harm's way...
