Fitting oval bangles

Hi,

I am trying to find on how to size oval bangles. I am
selling over the internet (Etsy), so my customers cannot easily
determine their size by trying on the bangles.

I checked all my books, but could not find any info on this. On the
internet I found this about round bangles:

XS 2-1/4"
S 2-3/8"
M 2-1/2"
L 2-5/8"
XL 2-7/8"

Does that sound right? Are those women’s sizes? If so, how about
men’s sizes?

I could not find anything about the sizing of oval bangles. Since
most of my forged bangles are oval, it would be great if somebody
could advice me on how to size those.

Thanks,
Birgit