Master Emerald (Classic Sonic's world)

The Master Emerald (マスターエメラルド) is an object that appears in the Sonic the Hedgehog series. It is another version of the Master Emerald from an alternate dimension set in the recent past. Like its counterpart, it is a massive gem of immeasurable power guarded by Knuckles the Echidna that is used to keep Angel Island floating in the sky.

Powers and traits
The Master Emerald holds unbound and infinite power in the form of extremely potent and raw chaos energy which can be harnessed to power and/or empower machinery, enable Chaos Powers and initiate a super transformation.

Past
The Master Emerald's early history was most likely largely the same as its mainstream counterpart's. The point of divergence occurred at an early point in the Master Emerald's recent history, when a Dr. Eggman from another dimension appeared in Angel Island's world during his trip through time in the Time Eater to change history.

Sonic Mania
In Sonic Mania, shortly after Sonic prevented Dr. Eggman's theft of the Master Emerald, the Heavy King, the leader of Dr. Eggman's Hard Boiled Heavies, made an attempt to steal the Master Emerald like his creator had tried before-handed. When Knuckles intervened, the Heavy King harnessed the gem's power to battle Knuckles, only to retreat without the Emerald upon being defeated.