Worry stones are smooth, polished gemstones, usually in the shape of an oval with a thumb-sized indentation, used for relaxation or anxiety relief. The smoothness of the stone is most often created naturally by running water.[1] Worry stones are typically around 3 centimetres in size.[2] They are used by holding the stone between the index finger and thumb and gently moving one's thumb back and forth across the stone. This action of moving one's thumb back and forth across the stone can reduce stress.[1]