Russian artist Alexandra Zutto has a great Adobe Illustrator tutorial about the image shown, detailing some of the finer points of Gradients in Illustrator.

In this tutorial, you’ll learn how to build up many elements to create a vector image with real depth and richness. Zutto explains: “I spend most of the time picking out colours that match each other to form harmonic colour composition. It takes a lot of time, but it’s worth the effort.

via Master dynamic gradient techniques – Illustrator Tutorial – Digital Arts.