JUDGING EXTERIOR EGG QUALITY
Grade A eggs must be clean. They may show traces of processing oil (used to preserve freshness).
Grade B - Eggs with:
Moderate stains covering < 1/32 of the shell if the stain occurs in one localized area
Moderate stains covering < 1/16 of the shell if the stains are scattered (i.e., two or more separate stains)
Dirty - Eggs with:
Moderate stains covering > 1/32 of the shell if localized
Moderate stains covering > 1/16 of the shell if scattered.
With adhering or foreign material larger than a speck (about 1.0 mm).
Small specks of dust or lint that may have settled out of the air should not be considered.