Gua Sha is a traditional Chinese medicine technique that has been around for centuries. 'Gua' means 'scrape' and 'Sha' means 'sand'.
It is a technique whereby tools, usually made from jade, bone or horn are used to scrape across the skin on the body to redirect energy flow. In doing this, stagnant energy is broken down, reducing inflammation, increasing blood flow and stimulating the lymphatic system to promote healing in the body. It’s a simple but rigorous technique which has been used for centuries to treat a range of ailments including muscle pain, tension, inflammation and migraines.
https://www.dermalogica.co.uk/blogs/skinspiration/how-to-gua-sha