I enjoyed the chapter. Depending on the spectral distribution of the enrergy source you could have pretty well any color by mixing 3 different colors, you could have some variety by mixing 2 colors. Video projectors use this concept, routinely. Doing it without wasting a lot of energy and having to disapate the waste would be trickier, using variable scources rather than filters would probably be the way. If this would be workable you could get any color with a clear focusing crystal which would presumably be easier to manufacture. Pardon my discourse. Thanks for writing. W.
No pardon necessary. Having worked with video systems (among other things) I'm well familiar with the inner workings of a CRT. I've decided to give Gred and Forge the multiple crystals around a common axis and surrounded in a diamond shell. With a little switching, they will have a blade that constantly changes colors. On the other hand, it will take them so much longer to make them, that they exhaust themselves and end up in the hospital. Harry is going to prohibit the rest from duplicating the effort.
Thanks for the input.