No, the Pic Discs are not a label, they are just oddities.
By the way, I bought all the afore-mentioned pic discs new + sealed.
I have heard somewhere, sometime (a long time ago), that the color affects the audio quality. Something to do with how soft the slab stays or how deep the cutting is. Ridiculous perhaps, but somehow it might be true. My reasoning is that colored vinyl sounds better than actual pic discs. No pic disc sounds as good as regular black licorice, I've got a slew of pic discs, and none compare to black top. I am sure that there are exceptions to this generalization, but, in general, this holds true my friends.