Rainbow Piece

The Rainbow Piece was a crafting material used solely to craft the Pot o' Gold, a pet-summoning item. This required 5 Rainbow Pieces. Rainbow Pieces used to fall from the sky, much like Fallen Stars, except that they fell during the day, disappeared at night, and only fell during the St. Patrick's Day season. They were slightly transparent.

Trivia

 * Because they had no sell value, they became almost completely useless once a Pot o' Gold was crafted.
 * The Guide referenced that the Rainbow Pieces are parts of a greater object, the Prism Danann. However, there was no such item in the game.
 * This may be a reference to the, a supernatural race in Gaelic mythology.
 * Due to the mechanics of both items, it was impossible for a Rainbow Piece and a Fallen Star to be dropped as items in the same world without one immediately disappearing.

History
Morceaux d'arc en ciel 彩虹片