A-Really-Expensive-Rock

Are you a multimillionaire that can't seem to find a gift for your multimillionaire friends? Look no further! This is a completely normal and generally worthless rock. However, wrap it up and give it to your friend for his birthday and it instantly becomes something he'll cherish forever. Imagine his puzzled look when he pulls a rock out of the gift bag, and looks to you for an explanation. Then you'll be able to look him confidently in the eye and say, "Be careful. That's a 500,000 dollar rock!" What a unique gift! He'll be so flattered! This rock is truly the perfect gift for the man that already has everything.