I have been looking for the designer of Gwen Stefani's shades for a long time. I settled with Ray Ban Wayfarers in Wood Print but I know it's not. And now, I know them. They are from Triwa and they are called Henry.
I do like the shape but I guess if it weren't for the print, this would not be interesting. Buy them at Urban Outfitters.
Or, you can buy this alternative from Ray-Ban.