It's really small, and @etoile de mer is absolutely correct in that the jump ring won't fit through it. I also brought a silver chain to try it out, and the little Tiffany bar also won't fit through.I am impatient and sometimes it has disastrous results. It did work in this particular case though.
What a tiny and frustrating hole size though.
I thought about getting a second Tiffany silver chain, taking it to my local jeweler and have them remove the jump ring/Tiffany tag, loop the chain through the starfish, then solder the jump rinb/Tiffany tag back on. But what a pain... and if ever need the piece serviced, I would have to take it back to the jeweler and have him undo it.
That said though, after seeing the posts in this thread, I'm going to keep it on the black silk cord. @etoile de mer posted her amazing starfish collection, and I now really like it with the black silk cord.
@etoile de mer I have a question for you... the loop where the knot goes through seems loose. Does yours ever fall out? Since my cord is 30" and I could just put it on over my head, I was thinking of taking it to my tailor and having her sew a little thread to make the loop smaller to be sure it doesn't fall out. I'm new to this black silk cord business! What do you think?