Givenchy vintage space-age silver necklace. Statement piece!

This vintage piece is the perfect necklace for fans of space-age and 60s/70s jewelry! It’s stamped Givenchy but I cannot guarantee its authenticity although I’ve done some research and it does appear to be legit.It’s got quite a bit of tarnishing and some scratches (please see photos) but still looks super cool on. It’s got a silver finish but I don’t know what it’s made from. I do love this piece but I just don’t wear it enough so I’m ready to give it a new home. I’ve attached photos of other similar pieces that I’ve found that legitimize the authenticity of it. Offers welcome.