the process you are talking about is called water marbeling here are the steps hth's
Marbling Prep
In this close-up on marbling we are going to take a look at marbling on tips or directly onto the natural nail.
For designing on tips make sure you prepare a skewer or chop stick by wrapping double sided tape around one end, this will be used to attach the tip to. Then apply a base coat to the tip.
For work on a natural nail be sure to have a cotton bud and nail polish remover ready.
Prepare the natural nail as per usual, wipe the surface of the nail with alcohol to remove oil and debris, then apply a base coat.
Timing is critical with marbling so being fully prepared is a must.
Nail polish hardens quickly on the water surface so as part of your preperation be sure to have all the bottles you are planning to use open and ready to go.
A~G: Fill a cup or glass with water, almost to the lip -90% full.Add the colours of your choice by placing each drop gently onto the surface of the water. Nail polish is the next important element in marbling.
The nail polish should be of good quality and of a liquid even consistancy. Poorer quality polish of inconsistant texture will not result in the desired effect.
H~O: Use a pin or needle, dragging it from one edge to the other to create the desired look. Experiment, have fun!
P: Insert the nail or tip into the water.
Q: Remove the excess nail polish while the tip is submerged. This is key to the success of this type of marbling.
R: Once the rough edges have been cleaned remove the tip from the water. NATURAL NAIL-Remove any excess polish from the surrounding skin using a cotton bud dipped in nail polish remover.
S: Apply a top coat NATURAL NAIL-Wash the hand then apply an essential oil moisturiser to the skin to prevent drying.
Heres the link
*BEAUTY & NAIL TIPS - A FOCUS ON NAIL ART(Marble) -*
it has some cute stuff on it.