The Chaos Emeralds are seven legendary gems that are sought out by certain people. When all seven are collected, it is said that a miracle can happen. Most people keep one as a lucky charm, if they do manage to find one.
The users may vary from time to time; after the Emeralds have been used, they shoot out into unknown areas. After that, the user has to find them again until they are able to reuse them. This is a list of the users so far:
- Sonic the Hedgehog: He is, by far, the most frequent user of the Chaos Emeralds, using them in most of his adventures.
- Shadow the Hedgehog: He used the Emeralds alongside Sonic in SA2, and against Devil Doom in ShTH.
- Silver the Hedgehog (technically): He used them alongside Sonic and Shadow during the "final" fight against Solaris. This is thought to have never happened, but Mephiles does make a prominent appearance against Malik, so this may be questionable.
An individual Chaos Emerald can grant increased powers. This is more visible with Shadow, allowing him to freeze or slow time with Chaos Control. If the user is exposed to an Emerald and suddenly loses the gem, (s)he will feel weakened due to their sudden drop of power.
When all seven Chaos Emeralds are collected, the user may access his/her Super state. Their Chaos abilities are also greatly strengthened. All seven Chaos Emeralds may be stopped by the Master Emerald, however.
The exact origin of the Chaos Emeralds is unknown. It is thought that the Chaos Emeralds came at around the same time as the Master Emerald, due to the fact that the Master Emerald can nullify the Chaos Emeralds.
Yep, this is pretty much what happened in the game. Don't be mad.
The Chaos Emeralds were scattered about the general area of Station Square. Multiple characters, including Sonic, Miles, and Robotnik, were on the hunt to collect all seven. Chaos, however, rebelled against Robotnik, and used the Chaos Emeralds' negative power to transform into Perfect Chaos. He proceeded to begin destroying Station Square. Sonic received the drained Chaos Emeralds from his friends, and harnessed the positive energy to enter his Super state. He defeated Perfect Chaos, and saved Station Square.