Color blocking is all over the place right now, nail polish trends included! It's pretty simple to do as long as you have some tape and a little bit of time. To achieve my nice straight lines I just used regular scotch tape and made sure to wait long enough between each color to make sure they were dry before I applied the tape.
The colors I used from left to right are Read My Palm, Teal We Meet Again, and Rumba Romance all from Sephora by OPI's Havana Nights collection. I LOVE this whole collection, especially these three colors together.