Pattern Index (Paint Seed)

Every skin carries a pattern index (also called a paint seed — the two terms describe the same underlying integer, just from marketplace-facing versus in-game-file naming) that determines exactly how a finish's texture is positioned on the weapon. For most skins this is invisible and doesn't matter, but for a handful of finishes it's the single biggest price driver there is.

Case Hardened, Doppler, Fade, Marble Fade, and Slaughter are the classic examples: two copies of the same skin, same exterior, can look dramatically different — and sell for wildly different prices — purely because they landed on a different pattern index. Marketplaces let buyers search by exact pattern index for skins where specific numbers are known to be especially desirable.