Most people don't smooth the edges. I do, and there are several ways to do it.

A quick way is to put all your pieces in a container and fill with water to the top of the pieces. Add a drop of dishwashing detergent. Gently shake and turn for about 20 minutes or so and take a piece out and check the edges. A clever way that someone wrote about is, she carries the container around in her car, back and forth to work, and by the weekend, the edges are smooth and she's ready to mosaic. I would set the container inside a cardboard box, just in case it leaked. I like to use those 48 oz. plastic containers that Texmati rice comes in because they have a wide opening.

Another way is to drag a kitchen sharpener across the edge, paying particular attention to any pointy areas. I buy kitchen sharpeners in the local hardware store. It's a carborundum stone with a wooden handle, and costs less than $10.00. It sounds like too much work, but it goes quickly.

Some people on here use an old ice cream freezer; they remove the paddle and tilt it at an angle in their kitchen sink (I think that's how it's done?). I haven't tried that myself.

Have fun and post pics, please.

Thank you all for the help! I was going to post a picture of my progress, but not sure if it can be done from my iPhone.

I always smooth mine. I either shake them in a cool whip container, or I put them in the rock tumbler that the wonderful CalamityJ gave me. Just 10 minutes. Then if I cut anything smaller to fit while I'm putting the mosaic together, I use a whet stone that I bought at the mosaic store. I keep it sitting in a pot of water an rub the freshly cut edge,
Kathy