[Jewelry making - Article 00201] - Re: [Orchid] how to measure the size of a ring

[Peter W . Rowe]

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>     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


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