I've seen some really lovely holo gradients around the nail blogging world, so of course on gradient day I had to try one.
I used all Wet & Wild polishes for this (again, haha), starting with a base of Metallica from the Wild Shine line. It makes a good base for sheer polishes, a little shimmer without color interference, and a little toning down of the shade for those of us who don't like the brightness that a white base gives.
For the gradient I used Blue Wants To Be A Millionaire and Hannah Pinktana from the Fastdry line. These both have scattered (nonlinear) holo microglitter in a very sheer jelly base, light blue and dusty pink respectively.
My camera doesn't do justice to the holo in these babies. I did get an intentionally blurred pic that shows it off a little better:
These are really nice inexpensive holos ($2!) even if they're not as blingy as some of the pricier options. It takes a few coats to build up the glitter, but it's lovely. Sponging it on gives more glitter and less base on the nail, to speed things up.