Crystal Key

"Resonates with large Red, Green, Blue and Purple Crystals."
The Crystal Key is used for activating crystals mainly found in Iolia Valley. Crystals come in 4 different colors and are activated by the respective key. Each color has a different effect when activated:
Red - Forms a breakable wall nearby, allowing the use of Rock Smash to enter new areas
Green - Crystallizes nearby rocks, allowing them to be destroyed by Rock Smash
Blue - Freezes nearby water, forming an ice bridge
Purple - Distorts a pathway to form a new one
==How to obtain==
Luna will give it to you after you rescue her from the altar in the Subseven Sanctum.