From Sonic Retro
The Crystal Ring is an upgrade available to Sonic in Sonic Adventure. It enables the hedgehog to charge the Light Speed Dash faster, as well as the superficial variation of changing the colour of Sonic's charged-up aura from blue to turquoise. Sonic Adventure is the only game where the Light Speed Dash requires charging by spin dash (having been switched to a single button-press from Sonic Adventure 2 onwards), and so this upgrade has not appeared anywhere since.
- Purpose: Allows Sonic to charge the Light Dash faster.
- Location: Station Square hotel. Climbing the stairs reveals a landing with two buttons; one to open a door on the other side of the lobby, and the other to generate a trail of rings leading to it. The Crystal Ring hides beyond that door, but it can only be reached in time by using the Light Dash.
- Requirements: Light Speed Shoes.
- Required For: Nothing--it's purely a novelty item to make Sonic's life easier when confronted with otherwise tedious charge times.