Speaking solely from personal observation, I’ve noticed that in America we tend to add “ish” when trying to catch the exact sort of color we imagine in our mind’s eye. “That robin’s egg is a greenish blue.” In England people often used “y” in the same way. “I love how robin eggs are a greeny blue.”
My dear sister-in-law was born on the spring equinox. I wanted to make a springy babushka, something with peachy pinky bits with mainly a greenish blue base. She has quite the sunny disposition.