Has anyone used an utrasonic jewelry cleaner to clean their coins? If so, then post your results and before and after pictures, if possible.

I tried my ultrasonic on some very dirty Lincolns using only hand dishwashing soap as the cleaner.
They result was less than desired.

However, as a fair warning... in the past I made jewelry, using mostly sterling silver chain. I did use the ultrasonic to clean some of the finished products after they had shown some discoloration. The result was spectacular... at least at the beginning. After storing the necklaces for a week I discovered they had totally turned a very unpleasant dark tone. Some would call it 'antiqued', but it was much too stark in appearance to be a natural antique toning.

Others may have had better experiences. As for me, my ultrasonic is in some recycling facility somewhere.

Corky

As a rule cleaning of coins destroys their value and is not acceptable by most collectors.

I thought you meant using soundwaves or something... lol... I'm generally afraid to go near much with chemicals; the most cleaning I've done is water to get dirt off pieces I've found on the ground.

Ultrasonic cleaning IS using soundwaves. I use it to clean samples all the time. It shouldn't hurt the coin because it doesn't use chemicals. You can just let the coin sit in H20. The only caveat I have for you is to watch out for bubbles forming on the coin when sonicating. They CAN cause some damage, but usually you don't have to worry about microbubbles.

Go for it! But I think it'd only help with larger dirt particles and getting dirt/grime out of crevices and whatnot.

The problem is not when you used the ultrasonic cleaner. The main issue is how can you guarantee that while the "cleaner" is doing it's job removing the dirt, grim etc that it will not hurt the coin. As well as, even if you are to remove it successfully, do remember that you have removed the stability of the surface.

Kind of what I was going to say. In addition to this, always remember that the greatest amount of anything on a coin is usually due to the combining of the coins metal with some other element. Example is the brown color of old Copper coins. This is Copper Oxide. When such things are removed from the coin, so goes some of the coins metal. This is one of the main reasons not to clean coins. Then too, as noted above, you remove sosmething that may actually be preserving the coin from additional damage.
Old saying: Let sleeping dogs lie.

I guess the real question here is: What exactly are you cleaning and why?

If it's metal detector finds, and your purpose is to remove enough crud to identify the coin, then I'd say go for it, I doubt you'd really be doing any damage. (Provided you don't leave it in there for days!)

If you are trying to remove a minor amount of discolouration, in the hopes of making it "shinier", then I'd tell Carl that you are dropping MS pennies on the concrete floor and send him over to your house! LOL