Master Emerald


 * You may be looking for the Chaos Emeralds.

The Master Emerald is a powerful magical gemstone from Sonic the Hedgehog's universe that is guarded by Knuckles the Echidna, being purported to be the only thing capable of controlling and neutralizing the power of the Chaos Emeralds.

Worlds Collide
The Master Emerald was mentioned in when Knuckles and Proto Man were battling Doctor Eggman and Dr. Wily's Egg-Wily Machine X. As it was empowered by the Chaos Emeralds, Knuckles lamented that the doctors hadn't stolen the Master Emerald as well so that he could use it to negate their power.

Worlds Unite
By the time of Sigma's arrival to the Lost Hex, the Master Emerald had been shattered and its fragments scattered across the planet. Sonic found one such shard near the Green Hill Zone shortly before being attacked by members of the Deadly Six, although he expressed some disappointment as he was hoping that it was the final Chaos Emerald needed to restore his world. Sonic's retrieval of the shard, would later be undone, though it would be recovered again at a later time by Knuckles.