It’s almost impossible to make a photo which will show this effect at its best, so please take a look on this video.
Don’t forget to choose 4K video quality.
Apply a medium thickness layer, hold a special magnet (sold separately) on a 2-3 mm distance for a 5-7 seconds. After that cure in UV lamp for 2 minutes or 30 seconds in LED lamp.
Don’t forget to purchase a magnet.