1. Sweep one stroke of blue (we like Zoya Nail polish in Breezi, $8; zoya.com) from base to tip along the left half of the nail.
2. Sweep black on the right side. Try Orly Nail polish in Liquid Vinyl, $8; orlybeauty.com.
3. Once polish is completely dry, use a white paint pen like Sally Hansen Nail Art Pen in White ($8; at Ulta) to connect the two halves.Read MoreLess