What standards cover
Dark tea sits under a recommended product standard in the GB/T series, as most tea categories do.
It defines what counts as dark tea and separates the loose forms from the compressed ones.
Ripe and raw material are described differently, because they are made by different processes.
The standard sets limits for moisture, ash, water extract and the amount of stem permitted.
Compressed products also carry a weight tolerance, so a cake does not have to weigh exactly 357 grams.
Sensory requirements are written out for appearance, liquor, aroma, taste and infused leaf at each grade.
Safety is handled outside this document, with contaminants in GB 2762 and residues in GB 2763.
Pu-erh additionally has a geographical indication standard, which covers origin and is separate again.
The standard number a producer worked to usually appears on the wrapper or on the outer box.
It can be checked in the public standards library, which is open to anyone at no charge.
What they do not cover
The standard will not tell you the age of a cake, which is the question buyers ask most often.
It sets no rule for how long a tea must be stored before it can be called aged or vintage.
It does not grade storage quality either, so a well kept cake and a damaged one can both comply.
Origin is covered only where a geographical indication standard applies, and not by the general one.
Market terms like old tree, single mountain and wild have no meaning inside the standard.
Blending across years and regions is permitted, which is common practice in this category.
Sensory checks are done by people reading words, so results are not perfectly reproducible.
Brewing parameters are not specified, and any instruction on the wrapper belongs to the seller.
Organic and similar claims come from other certification schemes, not from the product standard.
Compliance rules things out, and only your own tasting can tell you what is actually in the cake.
Two cakes pressed in the same year from the same material can diverge completely after ten years in different rooms.
Grades in practice
Grades in dark tea track the material more than the making, since the processing is largely fixed.
Bud content, evenness and the amount of stem are what move a sample up or down the scale.
Compressed products are graded on the material inside, and the shape of the cake plays no part.
The measurable numbers shift very little between grades, because they are floors rather than goals.
Grading happens within a lot, so the rank applies to that batch and not to the market.
The producer assigns it, and for dark tea that is usually the last word on the subject.
Age and grade are independent, and an old cake made from poor material stays poor material.
Gift and collector packaging leans on grade heavily, and the printed rank is often optimistic.
Loose dark tea sold without a grade is normal, and the absence tells you nothing on its own.
Use grade to guess at the material, then brew the cake and judge the result in the cup.
Safety versus quality
Safety and quality are separate questions in dark tea, and storage blurs the line between them.
Mandatory limits sit in GB 2762 for contaminants and in GB 2763 for pesticide residues.
The GB/T standard covering grade and composition is recommended, so meeting it is voluntary.
Moisture is the critical figure, because compressed tea is dense and dries slowly from the centre out.
Mould is the risk that follows, and no standard can reach into a warehouse to prevent it.
Fluoride is a genuine consideration in some brick teas, which is worth knowing if you drink a lot.
A named producer and a production date on the wrapper give you something to check and someone to ask.
Home mould and residue tests are unreliable, so do not let a kit decide anything for you.
Ask the seller for a batch test report, which established dealers can usually produce quickly.
Check safety through the paperwork once, then spend your attention on how the tea actually tastes.
A production date on the wrapper costs the producer nothing to print, and it tells you more than a grade does.