Here is my first go at gradient nails with 3 colours.
Colours used:
Base: Orly Jealous Much?
Middle: China Glaze For Audrey
Tip: Orly Prelude to a Kiss
Glitter: OPI Pirouette My Whistle
I used a dense sponge which was like a makeup sponge but didn't use the paint all strips on the sponge method though, so the gradient is not that smooth. Hence Pirouette My Whistle was used to try distract from the uneveness :p