The avarege jeweler, unless he or she has a one of a kind line,
depends on large national manufacturere for their bulk product. The
manufacturers set the average sizes years ago, not regionally, but
nationally. I started my apprenticeship in 1954 and that was
standard then as it is now.
There is no such thing a average, but if you start to think of it,
most of the time a ring has to go up or down a size or size and a
half. Any more sometimes will put an undue stress or distorton on
the ring. This can be overcome by multiple sizings, which is not
cost effective for the craftsperson. As most of you know, there are
very few jewelry store that employ jewelers today.
We see strings on this format , where can we get the cheapest work,
what country gives us the biggest bang for the buck. How little can
we pay for services, so we can make the big buck.
I am retired now, most of the time was lucky enough to do a great
deal of custom work. (As long as it was cheaper than factory made).
That way I never got rich, but did keep my pride in workmanship…