Since you posted a picture from my website I will chime in.
In my experience the red convexa generally only gets the green while in a color "transition state" - it goes from brown to green to red and a mix of there of until it finishes coloring up to rusty red. I find it only keeps the green accents under low light but when kept in insufficient lighting it grows much slower.
In the picture below that was taken this weekend from inside my display tank you can see part of a convexa colony in the left hand back ground.
