Two lots can both arrive with paperwork stamped "Grade 1" and taste nothing alike. That's because Vietnam's export grading and the specialty-coffee defect system measure different things, and a supplier quoting "Grade 1" is rarely specifying which one. Understanding both — and knowing which questions actually verify quality — is the difference between buying on a label and buying on the bean.
Two Different Grading Systems, One Word: "Grade"
Vietnam's domestic and bulk-export trade runs on TCVN 4193, the national standard used to classify green coffee by moisture, bean size, and defect percentage for commodity-scale contracts. Specialty buyers, by contrast, usually reference the SCA/CQI green-grading protocol, which qualifies a lot as "specialty" based on a defect count in a 350-gram sample plus a cupping score of 80 or above. A certificate that says "TCVN Grade 1" confirms the lot cleared Vietnam's commercial export threshold — it says nothing about whether that same lot would pass the specialty defect count or cup above 80.
Screen Size: What the Numbers on a Spec Sheet Mean
Screen size is measured in 1/64-inch increments and sorted through perforated screens, so "S18" means the bean is retained on an 18/64-inch screen. Vietnam's export grades typically require a minimum percentage retained on S16 or above for Robusta, and S15–S17 is common for Arabica lots from Lam Dong and Son La. A larger screen size generally signals more uniform roasting and a tidier-looking lot, but it is a size specification, not a quality or flavor guarantee — a large, evenly screened bean can still carry a defect load that disqualifies it from specialty grade.
Black & Broken: Vietnam's Core Commercial Defect Metric
TCVN grading leans on a blunt but practical measure: the combined percentage of black beans, broken beans, and foreign matter in a sample, alongside moisture content, which is capped for export at around 12.5%. Grade 1 Robusta typically allows a low single-digit percentage of black-and-broken material; lower grades permit progressively more. This system works well for pricing bulk, undifferentiated lots quickly at the port, but it bundles multiple defect types into one number and says nothing about cup quality, which is exactly where it diverges from what specialty buyers need.
The SCA/CQI Defect Count: What "Specialty" Actually Requires
The specialty framework separates defects into two categories. Primary (Category 1) defects — full black beans, full sour beans, pod/cherry, severe fungus damage, foreign matter — are serious enough that a single one disqualifies a lot from specialty grade outright. Secondary (Category 2) defects, such as partial black, partial sour, parchment, and insect damage, are weighted by severity and summed as "full defect equivalents." To qualify as specialty green coffee, a 350-gram sample must show zero primary defects and no more than five full defect equivalents from secondary ones, combined with a verified cupping score of 80 or higher. A TCVN Grade 1 certificate, evaluated only against black-and-broken percentage, cannot confirm any of this on its own.
Moisture and Water Activity: A Grade That Can Change After Export
Vietnam's humid, monsoon-influenced climate makes moisture control a moving target rather than a one-time measurement. Export standards typically cap moisture near 12–13%, while specialty buyers generally want 10–12% with water activity below 0.65 to limit mold risk during a multi-week ocean transit. A moisture reading taken at origin cupping weeks before loading can drift by the time the container reaches port, so buyers should ask for a reading dated close to the actual loading date, not just the figure on the original grading certificate.
What to Request From a Supplier Before You Buy on Grade Alone
A grade name is a useful filter, not a substitute for verification. Before committing to volume, ask for the TCVN grading certificate alongside an independent SCA-format defect count and cupping score pulled from a sample of the actual lot — not a general house sample. Request the screen size breakdown, a moisture reading dated near the planned shipment date, and, where the relationship allows it, a physical counter-sample to confirm the paperwork matches what's in the bags. Suppliers who can produce all four quickly are usually the ones already selling to specialty buyers regularly; hesitation on any single item is worth treating as a signal to slow down and verify before paying a specialty premium.
Grading systems exist to make coffee comparable across origins and shipments, but Vietnam's dual system — commercial TCVN grades sitting alongside the specialty defect count — means the same word can describe two very different standards of quality. Buyers who ask which system a "Grade 1" claim is actually based on, and verify it against an independent sample, are far less likely to be surprised when the container arrives.