This polish has magnetic particles in it. You paint your nails with the polish and while still wet, hold it up to the magnet that comes with the bottle for about 30 seconds. After, you come out with a beautiful star like pattern on the nail.
With the magnet it comes with (sometimes if you get your nail too close to the magnet, it will pull the polish toward it):
ETA: This polish was exclusive to the UK and is discontinued. I bought mine a year ago from ebay uk.