Lately I just haven't been satisfied with sticking to one color. For the look above, I started with shades (Barielle) Swizzle Stix:
Swizzle Stix looks like a regular baby blue but it actually has some green tones that make it closer to robin's egg. It's more blue than other Tiffany blues (like China Glaze For Audrey) but its green tones really stand out when paired next to a solid blue like OPI No Room for the Blues, which is the middle color here:
I meant to do this with tape for crisp lines but I was just too impatient to wait for each layer to dry, so the lines look a little wobbly.