I am in love with this! I discovered this on pinterest.com and it is SOOOO easy to do! Just don't mix too much, cause you'll end up wasting a TON of nail polish, and it is fairly easy to do with just a little of each. :) Here are the directions I found on www.heynicenails.com
Water Marble Tutorial.
Supplies: orange stick or toothpick, shot glass or cup (the smaller the circumference, the less polish you end up wasting), room temp. water, nail polish, tape (optional, but it helps with the clean up)
I like to begin by prepping my nails with base coat and one coat of polish. Here I used China Glaze Innocence for a nice neutral base.
1. Fill your cup with some warm or room temperature water. If the water is toocold, the nail polish will seize up.
2. Choose the polishes you want to work with; keep in mind the opacity of thepolish you are using, if its too sheer, it might not look right.
3. I like to begin with the lightest color. Load up the brush and let a big drop ofpolish fall into the water. Continue with the other colors until you have a fewconcentric circles of polish in the water.
4. Using the toothpick or orange stick, drag through the polish from the edgetoward the middle. Continue to drag the stick through the polish until you find adesign that you think looks pretty.
5. Optional: tape around the edge of the nail to protect your finger from becoming covered with nail polish. Scotch tape works perfectly for this.
6. Holding your finger horizontally, dip your fingernail into the glass, making sure it is completely submerged.
7. Use the toothpick/orange stick to trace around your finger, gathering up all theunused nail polish in the glass.
8. Lift your finger out of the glass, and let dry before taking the tape off.
9. Continue with your other nails until you have a full set of beautifully watermarbled nails.
10. Slick on your favorite top coat and Voila! All done!
Most importantly, have fun! As with any type of nail art, practice makes perfect, so don’t get discouraged if you don’t get it right the first time.