I don't know how much it will cost, but you should call EE Robins in Bellevue or Seattle. Their service is great and I know they will do a wonderful job! I bet your ring is beautiful ; )
My engagement ring was from there and I love it. They were quick when they re-sized it. If you are looking for wedding bands they have a great selection. There are customer friendly and will help you pick out or even design your dream ring. When my fiance was shopping for my ring he said they made him feel very comfortable and gave excellent service!