Start with the turquoise polish, I did 2 layers because I like the intensity of it better.
Cut small pieces of tape and put them on your nails so you can paint along them.
Do a silver layer. Wait until it's dry and remove the tape.
Put new pieces of tape about 1 mm lower than you did before (the silver is now partially covered).
Add the black polish, wait until it's dry, remove the tape and tadah!