"Did they cut the diamond so the all the light
from all angles is refracted directly towards you?"

No, that would cost way too much, it works fine as is.

Local watch smith/jewler is also a gunsmith. He knew exactly what I wanted. The original sight was made from steel and the diamond could not be mounted, so he reproduce it in sterling silver on a mini CNC mill. Including the tiny diamond it only cost me $180.00

Photo on the way.