From Specktra: Matching Blush and Lipstick to Eyeshadow
pink/plum blush-pink/plum lip-pink, purple, blue shadow
peach blush-peachy/nude lip-earthtone (moss green, browns, tans) shadow
coral blush-coral lip-bright color (think rainforest) shadow.
I don’t think there’s a rule, I just match cool to cool, and warm to warm. That’s about it.