I've got a green witch ball.
It is like a huge Christmas bauble, and they were meant to hang in the window. It is 8" in diameter. I paid £10 at an antiques fair for it, and have seen similar ones for £25-£30. I got it with a gilt chain (not old) hooked onto it, and funnily enough I was online just now looking up where traditionally it should hang!

Andrea

I'm going to hang it off the curtain pole in the dining room, where it will face the south.