The Sky Gem is a cyan emerald cut gem, similar in appearance to a Sol Emerald, that can be equipped on Sonic's Custom Shoes. When used, it allows Sonic to perform the Gun Drive to fly across long distances.
While having set Sonic's Custom Shoes to utilize the Sky Gem's ability, the Sky Gem changes their appearance into a cyan pair of shoes resembling Sonic's 2G Hi-Speed Shoes.
- Interestingly, it is possible to use a Homing Attack on the Sky Gem after the player throws it.
- Official in-Game description.