Some may find this interesting.
All coffee beans are graded before being sold, similar to diamonds. For a diamond, it is the 3 C's (cut, clarity & color), since it is all about the look to the eye. For coffee, it is all about the taste and smell. One of the ways in which you can tell how your coffee will be the best tasting cup with an awesome aroma is through the perfectness off each bean. Screen size is the the size hole the bean is sifted through, to ensure the beans are all the same size etc.
We only use Grade 1 coffee beans.
Grade 1: Specialty Grade Coffee Beans: no primary defects, 0-3 full defects, sorted with a maximum of 5% above and 5% below specified screen size or range of screen size, and exhibiting a distinct attribute in one or more of the following areas: taste, acidity, body, or aroma. Also must be free of cup faults and taints. Zero quakers allowed. Moisture content between 9-13%.
Grade 2: Premium Grade Coffee Beans: Same as Grade 1 except maximum of 3 quakers. 0-8 full defects.
Grade 3: Exchange Grade Coffee Beans: 50% above screen 15 and less than 5% below screen 15. Max of 5 quakers. Must be free from faults. 9-23 full defects.
Grade 4: Standard Grade Coffee Beans: 24-86 full defects.
Grade 5: Off Grade Coffee Beans: More than 86 full defects.
Source: Green Coffee Classification System Poster from the Specialty Coffee Association of America.