Well the answer to this question is there is actually no global coffee grading system. However, different counties export different varieties of beans and can grade them as desired.

Most beans are examined and graded based upon several criteria which are also the same everywhere in the world.

These include the altitude from their growing region, the region itself, the manner, in which they were prepared, and their shape or colour. Grading also includes determining what, if any, imperfections are visible on the beans. Finally, and probably most importantly, the taste of the roast that the bean delivers are also taken into consideration.

There are five grades from 1-5, which are broken down to indicate various imperfections of the coffee beans.

Types of imperfections found in coffee beans

There are three types of imperfections that can be found in a batch of coffee beans:

large stones

unripe beans

shells

One body known as the Specialty Coffee Association have introduced as close to a set of standards as you will find, and are explained as -

Grade 1

Grade 1 would be assigned to speciality coffee beans. These should have no inherent defects. There should also be no insect damage. If any do appear, and most batches will have a few, then there should be no more than a total of three full defective qualities.

When defects are involved, they refer to actual problems with the beans. For instance, black beans in a batch of dark brown beans would be defective. Blotchy beans also are considered defective. These are off-colour by their nature. In a green batch of beans these would be noticeably lighter in colour, perhaps light green or white.

Any beans affected by a drought are noted with ragged shapes and pale colours. These beans should be sorted so that a maximum of five percent of the beans meet the proper size. They have to meet a certain degree of quality for acidity, aroma body and taste. The beans should only have nine to 13 percent moisture content.

Grade 2

Grade 2 is assigned to premium coffee beans. These beans have to meet the same criteria as the previous grade. However, they cannot have more than six full defective qualities.

Grade 3

Grade 3 is a grade given to exchange coffee beans. These have to be 50% above the screening level and have a maximum of five quakers. Quakers give coffee a bitterness.

These beans must also be free from major faults and have no more than 13 defective items. Anything that sits in between 6-13 defects is classes as a Grade 2/3.

Grade 4

Grade 4 is given to most standard coffee beans. These can have anywhere from 24 to 84 defects.

Grade 5

Finally, Grade 5 is assigned to any off-grade coffee beans that have more than 86 full defects per batch.

So, as you can see, there is quite a lot of information used to grade the quality of coffee beans. For the average person though, it is not of any great significance. The coffee beans used in the UK market are all of good enough quality.

The grading is much more important to the suppliers and distributors of coffee throughout the UK.​