
Photo: Wikimedia Commons · CC BY 4.0
Thesis
Purple above green, needle above bud, rolled leaf above open leaf: this is a visual grading system. Purple buds were rare in Tang eyes; fat needle-like buds were preferred to thin ones; rolled leaves signalled tenderness and keeping quality. All three point to one standard: material should be plump, young and vigorous.
Modern famous tea still values plump, uniform, tender buds, but does not treat purple as a universal virtue. Purple buds may be rich in anthocyanins and may also be bitter; cultivar, season and processing change the result. Lu Yu’s standard is Tang experience, not a cross-cultivar formula.
What can be inherited is the order of judgment: leaf form first, plucking standard second, processing last. Using “purple is best” as a marketing phrase loses the method.
Source: 澎湃·茶经诵读一之源