I’m not sure what to tell you. Here’s what I can give you from your
American size 9 would equal a Japanese size 18
Japanese size 9 would equal an American size 5
but 16 mm is more like an American 6 1/2 or Japanese 13 If you’ve got
time, send over a set of cheapo plastic ring sizers and have them
send back the one that fits. . or. . .have them buy an inexpensive
adjustable costume ring, adjust it to fit, and send it to you.
Probably best is to have her go to a reputable Japanese jeweler, get
her finger sized in the Japanese standard or the American standard,
as long as they can tell you that the jeweler knew the difference and
they are correct in the they’re giving you. If you need
to convert from one to the other, the formulas are here and there I’m
sure, but I have a copy I got from Stuller’s findings book and I can
e-mail you a scan of it if you can’t find it.
David L. Huffman