So. Here’s the response from the lab. Doesn’t seem like a straight answer.
Thoughts?
"Organic chemicals in their pure form absorb light in all the colors of the rainbow. The particular color of a chemical depends on its structure, the solvent in which it may be dissolved, the pH of the solution, the oxidation state of its surroundings, the environmental temperature, and many other factors.
In the special case of cannabinoids, they are known to appear in various colors. For example, pure CBDV undergoes dramatic color changes depending on the particular solvent in which it is dissolved. CBN has two aromatic rings and is a strong chromophore, appearing pinkish brown when a solid and changing colors when dissolved in various solvents.
The mechanism by which pure cannabinoids come in different colors is likely a consequence of a transient resonance phenomenon of the olivetol phenol such that there is a certain minute fraction of time in which the aromatic structure shifts to a quinone, which would have a particularly strong chromophoric signature and color. If this hypothesis is correct, there is no such thing as a stable “pure” cannabinoid per se, but rather the existence of a mixture of resonance forms whereby the aromatic and quinone structures are in a dynamic equilibrium almost entirely dominated by the phenol. To test this hypothesis one would need to run a specialized NMR for several weeks in order to detect and characterize the rare appearance of the putative quinone carbonyl. The special conditions of each cannabinoid (e.g. cyclization, length of chain attached to the phenol, type of terpene dementhane structure, etc) would influence the chromophore intensity at various wavelengths, thus imparting unique colors to each cannabinoid under various conditions."