The Master Emerald is the biggest and most important of the seven Chaos Emeralds. It is the only Emerald where it is absolutely vital that it is in the Emerald Chamber at all times, otherwise the Floating Island will fall to the surface of Mobius below.
The Master Emerald was created, along with the other Emeralds, by the Drakon Empire as a means to storing the Chaos energy they had discovered. It was then stolen by Pochacamac and kept with the echidna tribe for the rest of its existance. Some time later, the Chaos Emeralds somehow split in half, with half of the Master Emerald finding itself in the Special Zone. Sonic the Hedgehog would find the Emeralds on two occasions and eventually keep them safe in North Cave, until Captain Plunder stole them. Sonic quickly retrieved them, but the Emeralds soon found themselves stolen again, this time by Doctor Robotnik and Knuckles the Echidna. In the Temple of Chaos, Knuckles restored the Emeralds to their original state.
For some reason, the Master Emerald returned to its former size (bigger than the other six) and was once again responsible for keeping the island in the sky. Robotnik, however, had different ideas and needed it to power his newly-restored Death Egg. Robotnik succeeded by ordering Metallix Mark 2 to steal it and brought it to the Sky Sanctuary Zone where a teleporter took it to the Death Egg. Sonic stowed aboard the Death Egg and, after a tough fight with Spikebonker and Eggrobo forces, was able to grab the Master Emerald and escaped the airborne ship. The Master Emerald landed deftly on the island's grass and Knuckles was able to return the Emerald back to its rightful place.
Later on, Doctor Zachary managed to find his way to the island and pretended to be the target of one of the Guardian Robots. In actuality, Zachary planned to use the power of the Master Emerald and ordered his robot to smash it and absorb the Chaos energy. Knuckles managed to stop Zachary's plan and witnessed him fall to his death off the island, but he no longer had a Master Emerald. Using the robot's head as a temporary replacement, Knuckles headed to the Kohenyu Graveyard, home of the island's Emerald mine. It wasn't an easy mission, but the echidna eventually dug up a raw Emerald and shaped it into a new Master Emerald. After a brief scuffle with the robot head, Knuckles was able to transfer the Chaos energy into the new Emerald.
CharacteristicsThe Master Emerald is more powerful than all of the other Emeralds (except, perhaps, the Grey Emerald). Thanks to this, several people and robots have been able to use its power to their own means. Both Metallix Mark 2 and Sonic were able to use the Emerald on the Sky Sanctuary Zone, the latter becoming Super Sonic after landing on it. The Guardian Robot that absorbed its power was able to fire limitless energy from its eye. When Robotnik absorbed the power of the Chaos Emeralds for the second time, he initially turned into a green statue, suggesting more of an influence from the Master Emerald. Much later, the Master Emerald was the last to be found by the Chaos Resonator belonging to Robotnik.
This list is related to events only important to the Master Emerald. A full list of list of appearances may be found under Chaos Emeralds.