I've started using gua sha a few weeks ago. I was frustrated because, despite loosing weight, my face still looked round. Until I read somewhere that it might not be fat, but water retention. I bought this one to try, since it was not very expansive (didn't want to spend a lot of money for a gimmick).
Unbelievable. In the span of one week, I could already see results. My face looked way less rounded, more oval, and you could finally see the limitation between my jaw and my neck. I am deeply happy with the result, and hope I'll get more in the future.
I've read somewhere gua sha has been used from centuries in China. It goes to show, the best broths are cooked in the oldest pans.