It shouldn't really make a difference but it can. Some form of orange/red is all I have ever seen in the ring on Yorkies.
Some judges will even discount you if you use any color of lead except black. Supposedly that's what you use if your a pro and know what your doing. I don't pay any mind to that hear say.
I may just one of these day even put my boy in 2 topknots and see what happens. I think they are cute that way too. LOL