I have got a vax s4. It's not meant for jewellery, it's just a steam generator for cleaning tiles etc, sit it on the worktop and press the button and a decent jet of stream squirts out.
It seems to displace crud quite well.
I think it's about 30 odd quid now, there are cheaper ones but I thought it worth a couple of quid more for the vax name and 2 year warranty.
I have a mid/cheap range ultrasonic and I just use washing up liquid and drop stuff in the basket, I don't notice any odd marks.
But, I probably produce in a year what you make in a day.