What do these gold markings mean?

by Denise
(RI)

I have a few old odd rings I inherited, and they have markings inside the bands that I can't seem to find online.

A gold wedding band, stamped 14K and "Bulard" inside. A gold ring with a green stone, stamped 10K and RGA inside.

This ring also has the letters SA inside a 4 sided square, but the top of the square is narrower than the bottom (don't know what that shape is called).

Lastly, I have a diamond engagement ring with the following markings inside the yellow gold band: B-N, followed by a small round hole that goes maybe half way through the band and is a little smaller than the letter N, followed by 14K.
Any help is greatly appreciated.
Thank You,
Denise