Wouldn't the silver tarnish and possibly stain your quilt? Seems like any coating on the silver to stop the tarnishing would flake off eventually from the eye end of the needle cracking through it.
I have a silver TJ Lane thimble, and was told that using it keeps it polished. I've had it for over 2 years and it hasn't tarnished yet.
http://www.thimbles2fit.com/