Which Silver alloy is suitable for Vermeil?

Hello to my favorite, all-knowing jewelry friends,

I have another “newbie” type question. I would very much like to cast
my new spring designs so that they can be turned into vermeil pieces.
I would like to know what type of silver the pieces need to be cast in
to be used for vermeil, is it fine or sterling? Next question…Does
anyone know a reliable source to do the gold overlay and turn the
sterling pieces into vermeil? I have never gone looking for platers
before and would rather trust a source given to me by my Ganoksin
friends. I live right outside Manhatten, so a NYC plater would be
much appreciated.

Thanks again,

Augest D.
Cry Baby Designs