For your consideration, here is an Older Stevie Nicks Oval Shaped Pinback Button, Pin.  It has some wear on it.  The back has a tarnish spot on it.  The button is 2 1/4 inches tall and 1 3/4 inches wide.  Item pictured is the actual item up for sale and comes from a non-smoking household.  (505.835o-.4px2)