YA Book Where Social Class is Based Off The Colors of The Rainbow

I have the vaguest memory of really enjoying this book as a little kid. Like the title says, what social class you were in was depicted from the colors of the rainbow. I'm pretty sure I remember red or orange was the lowest class, and violet was the bourgeoisie elite. I think I remember a scene where a kid is performing in a talent show, and the judges rate his ability by shining a certain color of light on the stage. Any help is appreciated, thanks 🙏

Edit: This was a fantasy novel