Wedding and engagement ring resizing is one of the most common requests made of a jeweler. There are multiple ways to accomplish this. We use the stretch it or compress it method for wedding bands, meaning we do not cut most wedding bands during this process. This means there is no 'join' and you do not lose any precious metals from your ring during the resizing process. However due to their very nature, rings with diamonds set in them cannot be resized using this method as it would cause damage to the setting(s) for the stones. These rings, like eternity and most engagement rings, are cut in order to have metal added or removed and then soldered back together.
The ring sizing machine is attached to a workbench and is the same tool that is used to make rings bigger and smaller. This method will not scratch rings.
The upper portion of the machine is used for enlarging a ring's size by stretching it on the ring mandrel. The process is actually very simple. After annealing (heating) the ring in order to make the process easier and to protect the integrity of the metal, it is placed on the mandrel so it falls to its current size marker. The lever is pulled which makes the mandrel and ring expand, and then released so the ring falls further down the mandrel to its new size.
The lower portion of the machine is used for reducing a ring's size by compressing it into one of several shallow round holes that taper towards the bottom to the ring's target size. After the ring is annealed the ring is placed in the hole that fits it just enough for the ring to slightly stick up above the hole. The lever is pulled and pressure is applied to the top of the ring to force it to fit completely into the hole causing it to be compressed in the process.
The wedding ring is now resized and ready for polishing and buffing to retain the same perfect finish.