Grading Scale
Enamel pins
A = best of the batch, very few flaws when viewed up close. Note that each is hand-filled by the factory.
B = more noticeable but still minor flaws, e.g. small bubbles in plating, small stray fibres in enamel, shallow scratches or dents, pin pricks in peripheral areas.
C = very obvious flaws, e.g. large stray fibres, oxidised blue/green blemishes, pricks or gouges in central areas, very poor plating, misfills. Random C-grade pins are available at heavily discounted prices or free for orders over certain amounts under the Weighted P4P/Freebie listing.
Glow effect designs
A-/B+ is an upper quality mixed grade that is good enough for most people, but not quite good enough for me! If you are only a bit picky, you can still get a nice pin with A-/B+. If you are very picky, you probably just want an A.
This is because a layer of clear enamel is added over the glow effect, which is a very fine powder, making tiny fibres or specks of dirt trapped between the layers more obvious than solid enamel or larger particle powders (e.g. pearl, diamond, glitter).
Pay-for-production (P4P) designs
P4P products are only very loosely graded so that the best of the batch go out first. They may have minor flaws, but defective items are removed during quality checking.
In purchasing a P4P item, you are acknowledging that what you receive may be anywhere from an A- to C-grade according to the above scale. I always endeavour to exclude C-grade items from P4P stock, but especially for preorder runs, this may not be possible.
Thank you for understanding!