I recently purchased an ultrasonic jewelry cleaner. Have not used it yet.
It is the type that no chemicals are recommended. Maximum cleaning time is 15 minutes with only water.
Am still trying to determine what to put in first. I know certain pieces should not be put in it. Those that are soft or have natural cracks, like opals. Very porous stones, like some chrysocolla. Unstabalized turquoise.
In the past I have used white toothpaste with a soft toothbrush to clean silver portions of jewelry that had turned black. That worked great. After cleaning, I rinsed the piece in water. Then wiped with a soft cloth.