It's not a new trend, but it's a cool one: magnetic nail polish! There have been many brands who have offered us magnetics, but usually at a very high price point. Claire's Magnetix are only $8.50 a bottle, with a pretty permanent buy one get one 50% sale. The premise of magnetic polish: you paint on a thickish coat, either over another polish for "underwear" or after your first coat of polish, then IMMEDIATELY place the magnet centered over the nail, and hold for 10-30 seconds. The magnet pulls on the pigment inside the polish, creating a beautiful contrasting colored design to the base polish. Here was my first effort:
These last few pics show the sparkle, and also how topcoat blurs and ruins the design. Might be better to forget the topcoat altogether.