A silly marble magnet question

[jagnightwalker.livejournal.com]

Ok, most instructions say to use 1/2 magnets. The standard (or what I would consider standard) marbles I've found are 5/8 inch. Most of the pics show the magnet as being approx the same size as the marble.

Are the magnets actually SMALLER then the front? I ended up buying 3/4 inch magnets but they are a wee too big, not enough to make a difference, but you still see the edge somewhat.

Thanks :)