I put a collar on Boo when I first got him b/c he's such a beautiful black cat. The collar was rhinestone studded but it didn't matter to Boo. He chewed through that thing in a matter of minutes. I put another one on him and he did the same thing. So no more collars for Boo or any of my Fur Posse. I've had up to 8 cats at once and none of them have had collars b/c they're all indoors and I don't see the sense in it. To each his/her own.