I always borrow the ultrasonic cleaner and some Alconox detergent from work when I want to clean jewelry. I don't see how you can clean jewelry without ultrasonics.
I've cleaned some rings that take a half hour of iterating between ultrasonics and picking at the dirty spots with a small brush until all the hardened skin oils are gone.
I'll send you my address so you can loan out that ultrasonic cleaner & increase the utilization rate. I'm not looking for oxygen clean service although that would work (does for valves).
What % ammonia/water?
I haven't tried this, but I have notes that tell me you can use a solution that is made with 3 parts ammonia to one part water for ultrasonic cleaning. It is used to clean some high tension parts in a scanning electron microscope.
Another cleaner for metal is called Micro-90.
I did the aluminum foil and baking soda the other day to a couple of really nasty looking silver coins. It pulled the tarnish right off with not work at all. Plus it doesn't remove any of the silver, the electrochemical process actually turns the tarnish (silver oxide OR something like that) back to silver. So you don't get any metal loss, like you would with polish.
I (my wife) bought this "special" jewelry cleaner at a home show.
worked realy good.
looked and smelled exactly like Mr. Clean floor cleaner.
Now we just use Mr.Clean at 1/20th the price.
Makes the gold and diamonds sparkle!