I... am not sure how to go about explaining this so I'll give it my best.

Alright... so in JEI or while holding the item/block... the Xen ore, leaves, sapling & wood cycles through the available colors like a RGB effect in a way. Y'know from red to orange to yellow to green, etc.

I don't suppose if it's possible to have the blocks cycle through these colors, like in the Xen Crafting Table you can pick the starting color and if the color cycle is enabled... it'll start cycling through all those colors. You could also have the option to have it act just like the ores, leaves, saplings & wood where it's given a color depending on where it's placed.

There could also be a 'color fade' effect where the color goes from bright to dim... if that's also doable but maybe the RGB Color Cycle is possible?

Currently the crafted blocks only allowed a static color, if... say you could apply a Color Cycle or a Color Fade, one could build a RGB Tower or some sort of glowing fading tower in a way.