Moon Crystals (月晶) are sources of great power in the world of Skies of Arcadia. They were created to control the Gigas of each civilization. Whoever holds the Moon Crystal commands the Gigas of the respective crystal. All crystals can be embedded into the silver Gigas, Zelos, upon which its master is able to call down the Rains of Destruction.
The Red Crystal, shaped like a tetrahedon.
The Green Crystal, shaped like a octahedron.
The Blue Crystal, shaped like a magatama.
The Purple Crystal, shaped roughly like a cylinder.
The Yellow Crystal, shaped like a cube.
The Silver Crystal, shaped like a sphere.