File:Chaos emeralds.svg - Wikipedia

Sonic the Hedgehog (franchise) - Codex Gamicus - Humanity's collective gaming knowledge at your fingertips.

Chaos Emeralds, The Codex Wiki

Steam Workshop::Godzilla and Transformers Uprising L4D2 Collection

File:Green triangle repeater.svg - Wikipedia

Game Theory (Stanford Encyclopedia of Philosophy)

Chaos Emerald, Sonic Wiki Zone

Chaos Emerald (red) by Flamethewolf1600 on DeviantArt

Chaos Emerald, Sonic Wiki Zone

Chaos Emerald, Sonic Wiki Zone