A while ago, Laure gave me 2 bottles of magnetic nail polish and a magnet from Essence (Thank you Laure :-) ). They didn't really work for her and I once said that I'd like to try it, so she just gave them to me.
To get this striped look, you need to paint and let the magnet do its work one nail at a time. The polish needs to be wet for the magnet to work. You need to put on a thick coat of the polish, slip the magnet over the index finger of your other hand and hold the magnet a few milimetes above the wet polish for about 20 to 30 seconds. Make sure the magnet never touches the polish. After waiting those few second remove the magnet and voila, stripes have appeared.
I do have to admit that the blue one works much better than the pink one (almost no stripes appeared).
A small tip from aunt Lilly ;-) : make sure you take the time when trying this. You'll probably screw up the first few times, you'll get too close with the magnet so your polish will stick to the magnet instead of your nails, you'll probably put the magnet somewhere between your bottles of base coat, top coat, polish remover and other stuff so that your nail will already be dry once you find the magnet hiding behind the magnetic nail polish bottle you've just used (yes, that actually happened to me), don't do this while watching TV, you have to keep the magnet still which won't happen when you're distracted, ... So don't despair. There is no magic trick, only patience.
So, thank you again Laure :-)