Green coffee is graded by counting defects in a 350 g sample, and the count determines whether it can be called specialty.
Category one — primary defects
The severe ones. Full black beans, full sour beans, dried cherry or pods, severe insect damage, and fungus damaged beans.
A specialty grade allows zero category one defects.
Category two — secondary defects
Partial black, partial sour, floaters, immature beans, withered beans, shells, broken or chipped beans, husks, minor insect damage.
Specialty allows up to five.
Why one bean matters
A single full sour or fungus damaged bean can taint an entire cup. This is not exaggeration — cuppers detect it reliably, and it is why the primary defect tolerance is zero.
Potato defect, common in some Rwandan and Burundian lots, is caused by a bacterium and makes a whole cup taste of raw potato. One bean does it.
Where they come from
Unripe or overripe picking, over-fermentation, bad drying, poor storage, insects.
Hand-picking selectively is expensive, which is why cheap coffee has more defects — and why it is roasted dark.
What you can do
Sorting a light roast by eye works: badly discoloured, shrivelled or pale beans can be picked out. On a dark roast you cannot see them.
Last reviewed 8 August 2026