Help! Trouble cleaning a moonstone in a sealed ring.

[meowkachu]

I recently got a 14k gold cabochon moonstone ring. The bottom is sealed. Somehow some grey particles got into the bottom of the ring. Since it’s sealed, I can’t clean it. I’ve tried ultrasonic cleaner and jewelry cleaning solutions, and none of them worked.
Do I have to take the stone off to clean its bottom?

 

[ForteKitty]

Closed back jewelry are a pain. You cant get them wet. There's no way to clean it unless the stone is removed.