Resizing a promise ring?

Hi, so my boyfriend gave me a promise ring and we are going to get it resized soon. Even though he got my ring size it is still a little too big/loose. I have never had a ring resized so my question for those who have does it come out flawless? I hear they cut a piece out of the ring and also is it expensive? I just want the same ring I have just smaller

Resizing a promise ring?
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