P2P is the starting material, not the end product - as it is not chiral (mirror image of it can be rotated to match original - whereas that is not true of a chiral molecule), any synth starting from it and generating a chiral product (meth, for example) will result in the racemate - 50:50 of the two mirror image isomers. edit: Interesting, not that I am surprised, but I never realized that racemic meth wouldn't make shards...
To get a chiral product, you either have to start with a chiral precursor (like pseudoephedrine), or prepare the racemate, and then separate the two optical isomers using some method which involves a chiral substance, such as forming salt with a chiral acid- the solubility of matching vs opposite chirality would be different, possibly different enough to separate effectively), or using chromatography with a chiral solvent (there may also be chiral chromatography media too, don't remember)... The guy who first discovered it had his lab assistant carefully sort crystals formed from the racemate of chemical, as it formed crystals with the matching isomer, so the crystals were actually mirror images of eachother; I would venture a guess that nobody has done this since. And in exotic professional synthetic organic chem, there exist chiral catalysts for some reactions. I do remember, way back before I actually did drugs and just read articles about how to synthesize them, I saw a procedure for using... I think it was d-tartaric acid... to resolve the optical isomers of (i think*) meth to get d meth from p2p-derived meth...
But anyway,yeah, it's food coloring, and in the process of breaking up, handling, etc, you'll find that the color can separate out. Even if they crystalized it with the dye in it,the dye would likely not be incorporated into the crystals, just on the surface/in cracks/etc. I would tell any dealer who tried to palm off dyed drugs on me where they could stuff those drugs! If they were okay putting an adulterant(dye) that was visually apparent to their product, who knows what other less visible stuff they might be adding... on principle, I would be inclined to refuse such dyed drugs, just like I would refuse something that was obviously cut. I think it's definitely partly an identity thing -my image of myself is someone who isn't so desperate for drugs that I'll accept obviously low quality product.
*could have been mdma too - I remember reading a discussion from the days of newsgroups with a few lucky people who had gotten to sample non-racemic mdma (apparently the two are responsible for distinct subsets of the effects)
