These hand painted metal hearts jingle when shaken. Put a harmony heart into a loved one's pocket or purse so when they here the ethereal jingle, they are reminded of how precious they are. Hearts are made from nikel-free metal. The heart has long been used as a symbol to refer to the spiritual, emotional, moral and intellectual core of a human being. As the heart was once widely believed to be the seat of the human soul, the word heart continues to be used poetically to refer to the soul and stylized depictions of hearts are used as prevalent symbols representing love.