Ultrasonic cleaners can be the big industrial ones mechanics and gun owners use, but I think for this use most people use the home version of the game, AKA a jewelry cleaner. I had one years ago and it's good for high end jewelry -- precious gemstones and metals -- but good for costume jewelry as well -- plastic, glass and basic metals.
It works by using gentle sound waves and warm water with a bit of cleaner. A few drops of Dawn et al would do it. If the vibrations were harsh it would knock the stones out of their settings, so it has to be gentle. It would take a ring or bracelet with years of gunk embedded and make it look almost new. As for rubber, it would be no harsher than putting a rubber spatula into hot dishwater except it would do a better job. Same for silicone. You could clean the pieces with a toothbrush and mild cleaner, but you would have to do it piece by piece and it may not get in all the cracks and crevices. With an ultrasonic cleaner, you just put in warm water, add cleaner, drop the pieces in the basket, and turn it on. The only caveat would be to get one large enough to handle what you want to clean.