I believe GS stand for Gora Stracenia, Unofficial badge worn by Battle of Lwow veterans, Commanded by rtm. Roman Abraham during Defence of Lwow (Lviv) in 1918.
I have the GS badge in my possession from 8 years, Found in the U.K. Screw on reverse, maker's mark Antoni Peczsz- Wilno. I want to verify the authenticity of badge. I have never seen a genuine one. What is your opinion on this? Thank you for any comments you can provide.