All pins are handmade, so there is no such thing as a "perfect" and "flawless pin" However there is a grading system I have in place. Such as "A grade"(minimal to no flaws) which is best of the batch and "B grade"(minor flaws), and "C grade" (flawed), which are the levels under. 

Pre-orders are guaranteed "A grade" aka the best of the batch of pins. 

A grade covers the surface of the pin not the back were the pin posts are or the edges. Which means A grade is the best surface pin with little to no flaws. This does not include the back of the pin or sides of the pin, only the design/surface. B and C grades are flawed surface designs. Sometimes even backing post flaws.

In hand will usually be a mixture of A-C grade. I grade the pins myself to determine the levels.