Colors: Y17, Y11
Using a brush nib, work your way in from the tips of the stars with Y17. Leave the middle open.
Soak the middle of the star with Y11, pushing the edges of the darker yellow out. Lightly feather the Y11 as you get further into the tips of Y17. This way, your edges stay soft and blend smoothly. Push with the lighter color until you get a smooth blend. If the dark color gets too light, add more dark again, feathering to keep from getting harsh edges.
Any lighter color will push a darker color out if the dark color is soaked enough. You can always keep layering colors as needed until the blend looks right. While blending, always keep a layer of scratch paper under your work in case the ink soaks through.