The cause of Huang Qin material and sugar color are the same, this is an undisputed fact. However, the color of yellow jade is primary.
The testing center in Xinjiang has been following this classification since not recently, but since the publication of the 1985 monograph "Gems and Jades of Xinjiang," which made such distinctions.
This isn't for the promotion of Hetian jade, but rather adheres to the main classification principles of petrology and mineralogy: causative classification, compositional classification, structural classification, etc. Nephrite (Hetian jade), after all, is both a rock and a mineral, and science is science.
Based on such classification principles, one can clearly distinguish between black jade and smoky green jade. High-quality green jade from Qinghai doesn't have to pass itself off as nephrite or be called something like "green nephrite."