Declaration on personal items- engagement ring

Hi there,
I live in China permanently when I Entry&Exit the country each time must I declare the personal use jewelry such as engagement ring and earrings?
Recently I have been fined by the German Customs as I did not declare my engagement ring which was over the certain required personal belongings value 430€. I was wearing the ring at the time of exiting,It is not for a commercial or resale purpose, the officer had barely took the ring of my finger. Horrific experience I am not even sure if this is legal ?