Gua Sha means 'to scrape'.
It is a Chinese Medicine technique that stimulates the lymphatic drainage system decreasing puffiness. It is suggested that a wide variety of skin conditions can be traced back to a stagnant lymphatic flow, because toxins trapped in blocked passageways will move out of the body in other ways. This can result in skin infections and breakouts. "When you can get your lymphatic system moving again, you are allowing potential excess waste lingering in those passageways to flush out."
It also encourages blood flow to area, giving you a glow and stimulating new cell growth.