18 K gold - marks

Having followed an earlier thread, would it be fair to say that if an
18K yellow gold stick pin or pin stem made a dark mark when going
through light colored cloth that the pin stem or stick pin is not
completely clean of polishing compound?? Or, does 18 K tarnish enough
to cause this problem. Thank you for your help. Sheridan Reed.

Hello Sheridan, Gold will leave a black mark on paper or cloth. The
higher the karat, the blacker the mark. I don’t know the reason, but I
know it is true. Have fun. Tom Arnold