Super Emeralds

The Super Emeralds are a second set of 7 emeralds found only in Sonic 3 & Knuckles. They are not found in either Sonic 3 or Sonic & Knuckles alone. To find them, enter any Sonic & Knuckles zone with all seven Chaos Emeralds, and jump into a flashing Giant Ring. These transport you to the Hidden Palace, where the player can jump onto one of the dull grey Super Emeralds and be whisked away yet again into a special stage. In Mushroom Hill Zone, there is one Giant Ring accessable to each character that always leads to a Super Emerald, no matter how many Chaos Emeralds have been collected. Collecting all 7 Super Emeralds unlocks Hyper Sonic, Hyper Knuckles, and Super Tails.

Note: If you already have all 7 Chaos Emeralds, Sonic and Knuckles can become Super, but collecting a Super Emerald cancels this effect.