You can try a gold polishing cloth.
Gold can tarnish. This happened to my Cartier earrings, and Cartier wanted to send it in due to “oxidation” and charge me something ridiculous so I decided against it and went home and used my polishing cloth, and it all went away!
Prior I used Dawn and water but nothing worked. I think I did what Cartier would have done for a lot less. Good luck!
Gold can tarnish. This happened to my Cartier earrings, and Cartier wanted to send it in due to “oxidation” and charge me something ridiculous so I decided against it and went home and used my polishing cloth, and it all went away!
Prior I used Dawn and water but nothing worked. I think I did what Cartier would have done for a lot less. Good luck!