|In canna chemistry, finished isolate products, even clear liquids and white powders, are not necessarily a determinant of purity. It is the same situation in the pharmaceutical world.|
Isolates can be +99.5% pure and may still have a strong color hue, even though they may be solvent-free and clean of impurities or adulterants.
To really confuse matters, a color change over time with cannabinoid isolates, or from different batches from the same producer, may NOT be evidence of a change in potency or purity. Since it can be, it is probably worth a question to your supplier. But remember it is not prima facie evidence of a problem.
The highest quality, most science-oriented processors who adhere to strict QA/QC protocols, rigorous internal process control testing, and pharma-world techniques should make a consistent cannabinoid product and it should have a consistent color hue. Proper shipping, handling and storage, as well as shelf life considerations and careful formulation and final product processing, is obviously required to avoid color changes.