Rainbow gem Sonic the Hedgehog

Answer 1

First, Gain All S Rank's on Every single mission, Town stage, Act, and Boss stage's. Then, Collect every single Soleanna Medal (Silver One's).You will then gain another Gold medal. By now you Should have got every single Gold medal there is to get. Finally, Get All the Acheivement's, then buy it from the store! Cost: 30,000 Ring's.

OR

Just hack your Xbox 360 Console.