Have you checked if Baking Soda is safe? That's what we use on silver in the gift shop but I've never tried it on Opals.

Ever Mind The Rule Of Three
Three Times Your Acts Return To Thee
This Lesson Well, Thou Must Learn
Thou Only Gets What Thee Dost Earn

Hahaha Fuck You Yuku! I have Lazarus!

Avoid MRSA: Join Hamster Smuggling for Life