The scale, top to bottom
Most graders use a 1–10 scale: a 10 is Gem Mint (near-perfect), 9 is Mint, and the numbers descend through Near Mint, Excellent, and down to Poor at the low end. Some companies add half-point grades and qualifiers.
What graders look at
Grades are based on centering, corners, edges, and surface. A card can be hurt by a single weak attribute — off-center printing or a soft corner can cap an otherwise clean card at a lower grade.
Why the top grades cost more
Because few cards earn a 10, gem-mint copies are scarce and command premiums over 9s — sometimes several times more. That is why value is always tied to the exact grade, which Slabline prices from real comps.