Mercari Jade's_Closet Ripoff and Mercari does not care for Authenticity I do not know Internet

Mercari does not care for authenticity. On June 18, I purchased on Jade's_closet a Cartier Love rigng band 18K for $250.00. the ring looked ok to me, I didn't rush to a Jewelry shop to get it checked.

I released the funds to the selle, a few weeks later the right started to get dull, I took it to a shop to get tested and it was not gold at all not 18K not 14K totally fake, and not Cartier for sure. I couldn't contact the seller to at least tell her she is a thieve becuase she was not selling anymore items on her page. I contacted Mercari and all they told me was too bad, I should have checked my item more carefully when I got it. Mercari has the name and bank information of the person that sold me the rign, the least they can do is contact them and not let them do business there anymore. Mercari sounded as if they really did not care at all. I will never purchase there anything of value.