I'm not sure... I picked up a Royal (purple) one for my son recently which was a lot lighter purple, and almost more blue, than a Royal stock I purchased ~2yrs ago. On the other hand, I picked up a Red & Black stock for him on the same order which is considerably more red than a same color stock from ~3 years ago. I got a "coyote" colored stock for my wife last year which is as rich and evenly colored as any stock I've ever seen from them...