Hi Andrew,
I have a Katherine Diehl in my ancestry tree. My Katherine Diehl was born 1882 and died 1936. She was actually Katherine Ritchie, then married Clayton Zacharia Diehl.
It's a beautiful photo; I am only related by marriage. My great-aunts husbands parents were Clayton and Katherine.
I don't have more information than that. Maybe it helps a little?
Julie