At the start of a hot stone therapy, smooth water-heated basalt stones are carefully applied to key points on the body. This direct heat relaxes the muscles, which means that the massage itself is more effective and intense than it would be otherwise. The size of the stones varies, according to which part of the body they're being used on. The stones are coated in fragrant oil to increase your sense of relaxation and calm. When oil is smoothed gently onto the body, each stone in turn can be worked along by the therapist's hands.