Like any natural product, each coffee bean is different - some bigger, some smaller, some longer, some rounder...that's lead coffee buyers many years ago to begin separating the coffee by the size of the bean.
Throughout the world, this is done by screens - like a stack of flat colanders, with each layer having slightly smaller holes in it than the layer above. Whatever the smallest size a bean passes through, that’s it’s size. In most places, they’re named by 1/64th inch - so a screen 18+ means all the beans are 18/64th of an inch or bigger. Simple, right?
Well...in Kenya they use the same screens, but give them different names. An “AA” is screen 17 and 18, an “AB” is screen 16 and 15 and anything smaller (but still a whole bean) is a “C”. There’s one more class you might have tried - “PB” or Peaberry. That’s a bit different again, but it’s usually separated from the other beans because the round cross-section of a peaberry lets it pass through the holes of a screen easily.
This year we will have the AA, AB, C and a Peaberry from Kiriga - so big beans, medium beans, little beans and even littler beans! Traditionally, the AA has got the highest prices (they’re about 15-20% of the crop), with AB being a bit cheaper and C going into commodity coffee. However, Brian from Kiriga sent us his C to try the year before last for the first time and we were wow-ed - it’s really sweet and nice - so we began buying it and are super excited to have it again for another year. The Peaberry has previously been included in with the C, due to the similar size and smaller harvests, however, this year the two have been separated out and there's enough of i to stand alone!