Phantom Ruby

The Phantom Ruby, also known as the mysterious gemstone, is an object that appears in Sonic Mania. It is a gemstone that contains incredibly powerful energy. Sonic the Hedgehog and Miles "Tails" Prower went to investigate this energy source, only for it to be discovered by the Hard-Boiled Heavies first.

Description
The Phantom Ruby is a red ruby that bears a resemblance to the Time Stones in Sonic the Hedgehog CD. It has the power to emit a wave of energy that can warp space time around it, although anyone caught in the wave will usually be sent to a different location. The ruby’s power can also be harnessed to create energy constructs and open portals.

History
The Phantom Ruby is discovered on Angel Island by the Hard-Boiled Heavies, and they use its power to send Sonic, Tails and Knuckles the Echidna to Green Hill Zone. They eventually give it to Dr. Eggman who abuses its power further.

Trivia

 * The sound effect made by the Phantom Ruby as it transports the protagonists to Green Hill Zone is the same as the one Infinite's attack makes in the Sonic Forces story trailer.