OPI's Alpine Snow (white) with OPI's Isn't it Precious? (pink)
Here's the how-to from a previous post, and here are the updated tips:
- Take your time, do it in bright light, and watch what you're doing.
- Let each coat fully dry before you add another one. See those grey spots in the pink above? Yeah, that's what you get when you get impatient and don't let them dry.
- Go all the way over the end of the nail every time or else you'll have a white (or whatever base color you used) edge.
- In my opinion, wide and even gaps between layers gives the best gradient effect. It seems to be more gradual and natural.
UPDATE: Here's a junky webcam picture to better show the range of the white to pink transition.