These look fab and it doesn't sound too hard to do.
1. Apply base coat to clean dry nails.
2. Apply base colour (one coat should afford sufficient coverage for this particular paint job) and allow to dry; I used Ciaté Sugar Plum.
3. Brush a small amount of a contrasting polish onto a sponge (I went with Topshop Gone Fishing.) Eyeshadow applicators are ideal for this job because they give you lots of control over product placement; alternatively you can use a cosmetic sponge. If you opt for the latter, I recommend trimming it down to size so that it’s no wider than the size of your nails to minimise clean up.
4. Immediately, gently press the sponge onto the tips of your nails. You may find that you need to do this a couple of times in the one spot to achieve a good colour payoff, which is fine; the important thing is to work reasonably quickly so that the polish doesn’t have a chance to dry out on the sponge. If you’re feeling adventurous, you could always sponge multiple colours across each nail for a many hued effect.
5. To achieve a subtle gradient effect, I build up the sponged colour in thin layers. I’ll cover the top half of the nail first and then move towards the tips with each subsequent layer so that the sponged colour is concentrated on the tips.
6. Finish with top coat.