Your ring stick is tapered and each marked division shows the ring
size at that mark.
According to my documentation, USA size 10 is a fraction bigger than
T1/2, but nearer T1/2 than U, so, if the ring is size 10 for the
entire width of 1.5" then it should slide onto the stick up to T1/2,
and no further, both ways round.
Frankly, a 1.5" wide ring is a tube rather than a ring and, in my
opinion, will be almost unwearable because it will cover up a
knuckle; still, if that’s what the customer wants…
I’m assuming that the ring is essentially solid, in that there are
no holes in it. If that is the case then be aware that wide rings are
difficult to size correctly. It’s not difficult to make a wide ring
of a particular size, but its difficult to determine just what the
size should be.
When the ring is being worn, the finger will sweat beneath it, and
the wider the ring the more difficult it is for the sweat to
evaporate. The moist skin under the ring then swells like it does
under a plaster (band-aid?) which can make removal of the ring very
difficult. This puffiness is known as maceration, and can lead to
bacterial or fungal infection.
The usual cure is to make the ring somewhat larger than measured,
but the difficulty lies in how much bigger. I once made a 1/2" wide
wedding band, one size larger than measured. After several months the
woman complained that the skin was all puffy under the ring, and
itched. I made the ring a size bigger, but the problem returned. I
ended up making it 3 sizes larger; the puffiness disappeared but the
ring was in danger of falling off when she was cold.
As far as I can tell, the shrinkage allowance for gold is around 2%
(someone will correct me if I’m wrong), which amounts to just under
a (UK) size for a T1/2 ring.
Regards, Gary Wooding