Enamel pins are manufactured by hand and no two pins are exactly the same.

A GRADE PINS
Pins sorted as A grade have zero to minor flaws only visible to up close inspection under white/neutral light or at certain angles. 

B GRADE PINS
Pins sorted as B grade have flaws that can be seen under normal light and simple inspection not located on a central part of the pin.

C GRADE PINS
These pins have flaws on either a central part of the design or on a big area of the pin, it's one or the other. 

What is considered a "flaw"
In this case flaws are considered blemishes on the enamel and plating such as:

 - Air bubbles on the enamel.
 - Uneven enamel filling.
 - Specs of dust on certain areas.
 - Rough patches on the plating.
 - Uneven polish. 
 - Missing enamel.
 - Wrong coloring.

All sales are final and non-refundable.