Does it turn after a while?

All I can say is that mine HAS NOT turned! I have not taken it off in 6 months. Swimming, yard work, sleeping, showering, etc. NO PROBLEMS!

What is the circumference of the clasp and the ring on the opposite side? I need a chain for my religious medals.

It is hefty chain. It might require larger eyelets. My cross would not fit.

Will this rust or change color if I wear it in at the beach or in a swimming pool?

Hi there,,I've been wearing gold colored stainless steel for over a decade,,,showers washing hands,,the beaches,,,,it is the most strongest n most durable metal in the world,,,,my jewellery looks,exactly like the day it was born,,,,it will scratch,,,,no friction on hard surfaces,,,it will scratch,,,,,,other than that,,,it's the best piece if jewelry anyone could own,,,hope this helps DEREK

Im 5'9 what length should i get?

I would get a 20". You don't want it hanging down to your belly. I am 6' with a 17" neck and a 20" fits me perfectly. Doesn't "choke" me. Sits just right. I guess you can get a 22 or24 inch too.