Ring sizing is by far the most common task I perform as a jeweler. The photos attached show a 14kt yellow gold gents ring needing to be sized up to a 8.5. First we cut the ring and hammer it up to the desired size. Then we cut a piece of 14kt gold to fit the opening. After the new piece is in place we weld it in place with gold solder. All that is left to be done now is filing, finishing, and final polish. When done correctly you shouldn't be able to tell that the ring had ever been sized.
When surprising someone with a new ring I recommend having the recipient come in for correct sizing. Many times customers guess at the size and more often than not are wrong. You really only want to size when necessary.
As always, feel free to ask any jewelry questions or concerns you might have.
By Stephan Werbeck