J.F.
I used to work for Rogers & Hollands in Brookfield Square, I would take it there. They have a Jeweler that comes into the store to do the work so the turn around will be quicker than most places, likely less than a week. The pricing will depend on the thickness of the ring, if you have two rings soldered together, and detail of the setting. If it is only one ring and only going up half a size, I would think it would be around $50, but I have been out of the business for three years, so don't quote me! Just make sure the associate taking your ring in writes up a detailed description and uses a diamond tester to verify your stones. Overall it is a very safe process and you shouldn't have any problems especially with such a reputable jeweler!