Ring stretchers can destroy a ring if not done properly. (or
attempted on an inappropriate ring style). The 8 spleen stretchers
are more forgiving because they spread the force around the
circumference more than the 4 or 6 spleen.
A couple tips:
The only rings that can be safely stretched are continuous bands. If
you stretch a ring with stones in it or a setting at the top be
prepared to remake the ring.
Anneal the ring before stretching it especially on older rings that
have been work hardened through wear.
As you stretch it you should consistently shift the ring so the
spleens keep moving to a different position and distribute the stress
around the ring.
If you can see or suspect a sizing line keep that spot on the solid
part of a spleen so you don’t stretch the solder because the solder
Lastly, flip the ring every 1/4 size so you don’t end up with a cone
shaped inside or pass the size you want.
As for rings with stones:
There is a tool that vigor (and others) makes that will roll the
bottom shank portion of a ring to enlarge it. This can be a handy tool
at times. It comes with a variety of dyes to match the shank shape
too. A word of caution…it’s easy to warp the shank if done
incorrectly. It’s best to size vs. stretch since the latter will
thin the shank. I use this tool to even out sloppy shanks from
previous work or to go up only a fraction of a size on rings with