My father was born in 1915 and his middle name was Diamond. He always said it was a family name (which I took to mean a surname) that only the men took on. However, having studied his family tree I have found no evidence of this. Also, his mother tragically had a little girl who died before she was 2 years old called Ruby, so I think she just liked the names and the meanings behind them. I was nearly called Diamond as a first name according to my mum, but my father didn't like the idea of a girl having the name.
This name is also a Masculine name used in Nigeria and Ghana.
https://forebears.io/forenames/diamond
https://www.popular-babynames.com/name/diamond
https://names.darkgreener.com/#diamond
According to the USA Social Security Administration, 132 girls and 54 boys were recorded with the name Diamond in 2022.
https://www.names.org/n/diamond/about
https://www.nancy.cc/baby-name/diamond/
A notable Masculine bearer of the name is a basketball player: Diamond Stone.
His birth name is Diamond Louis Stone.
https://en.wikipedia.org/wiki/Diamond_Stone