My customer received two lovely silver rings for Christmas, made by another Etsy metalsmith. However, it turned out that they both needed to be half a size larger to fit her comfortably.
A half size is a relatively small amount, but I didn't want to try to upsize them by stretching them because the shanks were thin and delicate to begin with, and the design on the leaf shaped ring at least, would certainly have warped.
Instead, I cut open the shanks in the back with my saw. After checking a ring blank sizing chart I knew each ring needed to gain about one millimeter in circumference, plus what was lost when I cut open the backs. So I cut two small pieces of 16ga sheet and inserted them into the opened space:
Then I fluxed, soldered the sizing stock into the shanks with medium solder (I generally like to use hard for everything possible, but again I wanted to reduce the risk of overheating the existing joins), and pickled:
I used a coarse half-round file to shape the added metal as closely as I could to the surrounding shanks, inside and out, leaving just a bit of extra metal to allow for sanding:
Finally, I sanded the shanks until smooth and blended, and polished with Zam: