Bag of Jewels

{t}: Put the top card of your library onto the
battlefield face-down. It becomes a Treasure.
(It's a colorless artifact with "{t}, Sacrifice this
artifact: Add one mana of any color.")
{2}, {t}: Return target non-token Treasure you
control to its owner's hand.
For all the turmoil they have caused, these precious
gems are simply shiny rocks.