- You may be looking for Mobius Prime's Chaos Emeralds, the Sonic X Zone's variant, or the ones from the Another Time, Another Place reality.
The Chaos Emeralds are magical gemstones charged with the energy of the Chaos Force from the reality of Dark Mobius. Their history is presumed to be largely identical to that of their counterparts from Mobius Prime.
In order to combat the growing threat of Dark Enerjak, Sonic the Hedgehog gathered the Chaos Emeralds and used their power to transform into Super Sonic. Unfortunately, he proved no match for his former ally, who took him prisoner and claimed the Emeralds for himself, ensuring that no one would ever be able to use their power against him again. (SU: #28)