Why the gap exists
A PSA 10 ("Gem Mint") signals near-perfect centering, corners, edges, and surface. For sought-after cards, far fewer 10s exist than 9s, so scarcity drives the premium. The thinner the 10 population, the bigger the gap.
See it on real cards
The premium is easiest to understand by looking at actual cross-grade prices. Each Slabline card page shows the value at every grade side by side:
When to chase the 10
Chase the 10 when the population gap is large and the card is a long-term hold — the premium tends to widen over time for iconic cards. Lean toward the 9 when the gap is small, you are buying to enjoy, or liquidity matters more than ceiling.
Whatever you own, Slabline values it at its actual grade from real comps — so you always know where you stand.