If you have a couple of rough spots, they can be ground with sandpaper or diamond pads that are available and in many hardware stores. You can, of course, also use a belt sander if you have one. I have seen some people leave the glasses with a ground and therefore whitish-looking edge, but I prefer to take the finishing of the rims a step further. There are two options in trying to achieve a smooth and shiny edge. One is to use a kiln, the other is to use a propane torch.
If you have a kiln, you can place your item in it and fire them to a low temperature, which heats the glass up just enough to do what we call fire polishing. The advantage of a kiln is that you can fire-polish quite a few items with one firing.
Using a propane torch is a bit more exciting. You need to place the item half on a non-flammable surface and then, while wearing safety glasses and gloves, hold the flame about 10 inches away from the glass and slowly heat up the glass while moving the torch around. The best way is to have a lazy susan that the glass can be rotated on while heating it. Eventually, the glass will get hot enough to also fire-polish the edges. Make sure to let the glass cool off before attempting to move it in any way.
—Ruth Dobbins, EtchMaster