To stretch a wedding band that is larger than your ring stretcher mandrel, slip a copper sleeve over the mandrel and place the ring over the sleeve. The mandrel will press out on the copper sleeve, which in turn will press out on the wedding band stretching it to a larger size.
To make the sleeve purchase a 3/4 inch copper pipe coupling from a plumbing supply store. Then using a hacksaw, cut slits down the length of the coupling. Make four to six cuts to line up with the slits on the mandrel on your stretcher. Make all the cuts from one end and cut 3/4 of the length of the coupling. This will allow it to expand and will make it easier to remove the ring when finished.
Measure the thickness and width of the ring shank and record these measurements on the job envelope before you begin sizing the ring. Having these measurements may save you from doing a half-shank later if the customer complains that you thinned the shank too much during sizing.
The difference in one size is 1/10 of an inch or 2.54 millimeters. For simplicity 2.5 millimeters is used in actual practice. lf a ring is to be sized up or down one size2.5 mm is either added or removed from the shank.
Sizing Wedding Bands that are engraved or have other decorative finishes can create problems when trying to size down. First anneal the band. Then, wrap the band in a strip of thin leather.
Next, place the band wrapped in leather in the compression die on a standard ring stretcher.
The leather will protect the finish, allowing you to reduce the size of the ring in the same manner as a plain polished half-round band. Touch up the polish with rouge, and the band is ready to go.
Always anneal wedding bands priorto stretching orcompressing with a ring stretcher. Die struck seamless bands are worked hardened during the manufacturing process. This hardened gold is difficult to stretch or compress. Annealing the band before you begin will reduce the amount of physical force that you need to apply to accomplish the task. A ring stretcher is not designed to double as a nautilus machine. In addition, if the metal is not annealed the stretching or compressing process may cause the metalto crack.
To measure the size of a finger with a large knuckle, take an inexpensive set of plastic ring sizers and cut a slit in them with a fine saw blade. Then when measuring with them, they will open to go over the knuckle and you can measure the finger for a proper fit ofan adjustable shank.