|Master Emerald did not originate from fanon, and more information can be found on their respective wiki(s). You may read more about it on the following wiki(s):|
The Master Emerald is an item in the Sonic series. It is the supervisor for the Chaos Emeralds, meaning that any damage to it needs to be amended as soon as possible or the results will be disasterous (an example being the collapse of Angel Island at the start of Sonic Adventure). Invariably it is guarded by Knuckles, usually in isolation (the most notable exception to this rule is Sonic Heroes 2).
In this game, it is guarded by Shade and Knuckles, owing almost entirely to the obnoxious infatuation of both parties towards each other in that game.
Super Mario Silver Spurs Trilogy
Super Mario and Friends: Zennu Quest
Here Evil count Dorkula tries to find this Emerald to use its power and conquer Zennu, Mushroom World and Real world in same time.