This is my take at 'dip dye' nails, i am no expert with nails i just like to experiment and have seen a few designs like this on other blogs and throughout tumblr.
All you will need is...
A base coat, i have used this nail hardener from boots which works just as good. Two different coloured nail polishes, i have used 'mint candy apple' by Essie and 'vintage pink' by Models own, you can use any two nail polishes you want to achieve dip dye nails. Plus some sort of sponge - i use a clean cleaning sponge, and rip a small piece off when needed. Lastly you will need a top coat which i forgot to picture, but any top coat will do.
Firstly I applied my base coat to the nail, then two thin coats of 'mint candy apple' to build up an opaque colour. With my second colour, 'vintage pink' i applied to the tips of my nails - this step does not have to be so neat as the line between the two nail polishes will be covered, just make sure the layer of nail polish applied is quite thin, but still thick enough to cover the over colour.
Next, to achieve the 'dip dye' effect I take my sponge and dip it into the second colour nail polish - to make it easier i drop a bit on to a piece of paper or old magazine. With the sponge i then begin to dab lightly where the painted nail tips meet the other colour.
Finish with a top coat and enjoy your dip dye nails.