Hear me out! We've all observed people wearing chokers for a while. They're a simple way to add a little edginess or elegance to any outfit. But designs are usually so simplistic that they're not usually thought of something that can be matched.
Collars, or chokers, as a "friendship necklace" is a great idea because it gives you another fashion article to coordinate with someone else. Collars in particular are usually more ornate, so not only will you be wearing something that matches with your friends but is genuinely more pretty.