i dont want to throw a spanner in the works but im sceptical about the substrate thing although i cant rule it out. ive heard this from the very first time i kept marbles and ive swapped substrate many times as have others but im not sure it has been of any benefiit.
dont get me wrong im not saying that these rays wont look stunning in another 12 mths. im just saying that they might change without swapping the substrate or if you change something else instead of the substrate. i think some people have changed the substrate and they have decided thats the reason the rays started to look better when actually it could easily be something else or just that the rays coloured up on their own.
at the end of the day i dont suppose it will hurt anything if you do change the substrate but maybe lots of us are under the wrong impression about marbles and substrate.
edit :
just wanted to point out what aquaman said in his original reply :
" if they don't make the grade then I will sort you something out Steve, swap them with another pair or something, I want you to be happy. Lets give them a while longer yet, its still early days. "
credit where credits due. you cant argue with that whatever they turn out like. well done aquaman/wharf aquatics.