I used the neon orange and yellow from the Wet N Wild Saved By The Nail Collection. Pin 'Em Slater & Straight A Jesse. Then I stamped the 2 citrus images from BM 308 using Konad Special Black Polish.
This is the gradient prior to the stamping. I just painted 2 coats of white polish and then used a makeup sponge to blend the two colors on top of the white.