I usually tie my lanyards with the same line as my running rigging which would be a light color (not black).
However, on some real ship photos I have seen these rigged w smaller diameter black.
The reason for this post is that I had a non member ask me about lanyards. Instead of trying to explain. I posted this image. Then gave him the link to this thread.
I am not sure if the non member ever visit this post as I have not gotten any reply.