^^^ I've heard that too. Also, I have lots of emeralds, which aren't supposed to be put in an ultrasonic thing.
I clean my ering/wedding band with GemCare (no ammonia) every morning - just let them sit in there while I do my makeup and hair. If they're especially dirty or caked up with lotion, etc, I give them a little rub with a soft toothbrush. For when I'm not wearing my everyday rings (including ering/wedding band), I keep a Waterford ring holder on the bathroom counter, and put my diamond studs in the base of the ring holder as well. In a pinch (like on vacation), I use toothpaste and a little tiny toothpick brush (the kind they sell with dental floss - teeny little brush for between teeth, which takes hardly any room in my travel kit) to clean my diamonds.