I need a little help understanding the correct way to measure the
size of a ring. Especially wide rings.
The main thing to understand is the size of the ring is a function
of it’s inside diameter at it’s smallest point. I say that since
many rings have a “comfort fit” convex inside, or a beveled inside
edge. So when you measure a ring with a mandrel or 'ring stick",
what you have to do is read the size where that minimum inside
diameter is contacting the stick. If the ring is a good cylinder
inside, not tapered or “comfort fit”, then the measurement will be
at the leading edge of the ring, where that edge jams tight on the
stick. If the ring is “comfort fit”, then the actual contact area
will be close to the center line of the ring, not it’s edge. So how
you read the size of a given ring depends on it’s inside shape.
Now, how you determine what size a ring should be differs from just
sizing the ring, and depends on how closely the sizing bands you’ve
used match the width of the ring to be fitted. Wider bands tend to
feel tighter than narrower ones of the same size, so if you size a
finger with narrow sizers, then a wide band made for that finger
will need to be a little larger in size in order to fit the same.
How much larger depends on the person, but an 1/8 to a 1/4 size is
common.
My concern though is that the dang thing is only 10 inches long
including the handle. Is that too small to accurately measure a
ring?
The shorter length just means it tapers more quickly. What’s
important is that the sizes be accurately marked, not the degree of
taper. Some of the cheap ring sticks are not very accurately
marked… Remember what I say above. The size is where the minimum
inside diameter of the ring contacts the stick. Now, a comfort fit
or tapered band, if it tapers more slowly than the mandrel or ring
stick used, will be harder to measure, since then you have to sort
of guess. But you can come close.
Frankly, if you wish accurate sizes, for my money, I’d skip those
light weight sticks all together, and just get a good, accurate,
steel mandrel. That’s the actual tool used to size the rings for
real, when adjusting the size, rounding them out with a mallet, or
whatever. Unless all you’re doing is front counter ring sizing, the
sticks aren’t as useful. They’re merely a lighter and cheaper
substitute for the most part (with perhaps, the exception of ones
like what I think you describe, which may have several scales on it,
which can be convenient when converting, especially from the
european metric ring sizes to the U.S. ones) In buying mandrels, I
prefer the american made ones from the jarvi company. Good accurate
markings, properly tempered steel, and well finished.
Also, in sizing stone set rings, remember to always check whether
culets of stones project through the ring. If so, use a grooved
mandrel so the culets aren’t jammed against the mandrel (they’ll
chip. even diamonds…). even the softer plastic ring sticks can
force a stone loose in it’s mounting if it’s culet is jammed against
it.
peter