This may be rehashing old information, but there are three (and probably more) types of micarta. Paper has the finest "grain", followed by linen and canvas is the coarsest grain. The "grain" may not be detectable in good paper micarta, but it can easily be seen in linen and canvas.
Exactly how this relates to Westinghouse, "ivorite", yellow or gold micarta as used for Randall knife handle is not clear to me.
I told Rod in a private conversation that I thought the color changes seen with some micartas are probably due to differences in the chemicals used and/or the exact process by which the stuff is formed.
Certainly, some colors do not change and some change quite rapidly. For instance, the so-called Westinghouse yellow micarta that was being sold on eBay a couple years ago. That stuff has been discussed here before and changed from yellow to brown quite quickly.

- - - -Buckspen