Every CS2 skin instance carries a hidden integer between 0 and 999 called the pattern index. For most finishes this number is decorative — it shifts the texture's UV mapping by a small amount and produces no notable visual change. For a small number of finishes, the pattern index is the single most important determinant of value, with specific indices producing collectibles that trade at 100× to 1,000× the base finish price.
How the pattern index is generated
When a skin instance is created (via case opening, drop, or trade-up), the pattern index is rolled with uniform probability across 0–999 independently of the float and rarity rolls. The mapping from pattern index to visual outcome is finish-specific:
- Most finishes apply the pattern as a small UV offset, producing no visible difference between, for example, pattern 100 and pattern 800.
- Color-banded finishes like Case Hardened use the pattern index to shift the position of color regions, producing dramatic visual variation.
- Doppler family finishes use the pattern index to select among phase buckets (Phase 1–4 + gems), where each phase corresponds to a specific range of pattern indices.
- Marble Fade and Fade use the pattern index to determine which color combination and gradient direction applies, with collector tiers based on visual outcome.
Case Hardened blue gem patterns
Case Hardened is the most pattern-sensitive finish in CS2. The blue, yellow, and brown color regions on the skin's surface are positioned according to the pattern index, and a small number of indices produce a near-fully-blue surface — the so-called 'blue gem' patterns. The most established blue-gem indices for the AK-47 Case Hardened:
| Pattern | Blue % | Tier | Approx. recent transaction price (FT) |
|---|---|---|---|
| #661 | ~95% blue + scope | Tier 1 (BUFF #1) | $150,000+ |
| #321 | ~90% blue | Tier 1 | $80,000–$120,000 |
| #151 | ~85% blue | Tier 1 | $60,000–$90,000 |
| #179 | ~85% blue | Tier 1 | $55,000–$85,000 |
| #955 | ~80% blue | Tier 2 | $25,000–$40,000 |
| #168 | ~78% blue | Tier 2 | $22,000–$35,000 |
| #387 | ~75% blue | Tier 2 | $15,000–$25,000 |
Karambit and knife Case Hardened patterns
On knives, Case Hardened patterns are tracked by community pattern databases that catalog every pattern index for every knife type. The original 'blue gem' standard — Karambit Case Hardened pattern #387 — set the precedent for blue-gem collecting and remains one of the most expensive single skins ever transacted in CS2 history.
| Pattern | Description | Tier |
|---|---|---|
| #387 | Blue spine, near-fully-blue blade — original 'blue gem' | Tier 1 |
| #231 | Heavy blue with minimal yellow | Tier 1 |
| #601 | Blue blade with clean spine | Tier 1 |
| #888 | Pearl-blue tonality across blade | Tier 2 |
| #592 | Blue-dominant with light yellow accents | Tier 2 |
| #896 | Blue gem with small yellow patch | Tier 2 |
Marble Fade tier system
Marble Fade uses the pattern index to determine which color combination and gradient direction is rendered. Collectors classify Marble Fades into established tiers based on visual outcome:
| Tier | Name | Visual signature | Approx. incidence |
|---|---|---|---|
| Tier 1 | Fire and Ice (FFI) | Pure red and blue gradient with no green | ~1.5% |
| Tier 2 | Tricolor | Red, blue, and yellow in even proportions | ~3.5% |
| Tier 3 | Max-Fire | Red-dominant, minimal blue | ~5% |
| Tier 4 | Standard | Mixed proportions, no specific tier signature | ~90% |
An FFI (Fire and Ice) Marble Fade Karambit, for example, regularly trades 4–8× the price of a standard-tier Marble Fade Karambit at the same float. The premium reflects both visual desirability and the ~1.5% incidence rate. Within FFI, additional sub-tier classifications exist based on the precise color positioning — a 'true' FFI with no green visible from any angle is rarer than a 'near-FFI' with very minor green at the edges.
Fade percentage math
Fade is a different finish family that uses the pattern index to determine the gradient quality. Unlike Marble Fade, Fade does not have named tiers; instead, collectors compute a Fade percentage that represents how much of the desired purple-to-yellow gradient is visible without distracting elements. The standard formula varies by knife but generally follows:
Fade% = base_min + (pattern_index − pattern_min) × (base_max − base_min) / (pattern_max − pattern_min)Most Fade knives produce a Fade percentage between 80% and 100%. Collectors typically distinguish three brackets:
| Fade % | Bracket | Approximate premium vs. 80% baseline |
|---|---|---|
| 80–84% | Lower bracket | Reference (1.0×) |
| 85–89% | Mid bracket | 1.1–1.3× |
| 90–94% | High bracket | 1.4–1.8× |
| 95–99% | Top bracket | 1.8–2.6× |
| 100% | Full Fade | 2.5–4.0× |
Where pattern index does NOT matter
For most finishes, pattern index is purely decorative. AK-47 Redline, AWP Asiimov, M4A4 Howl, and the vast majority of weapon finishes show no observable difference between a pattern 1 and a pattern 999. Pattern-sensitive finishes are concentrated in:
- Case Hardened (and Heat Treated variants)
- Doppler / Gamma Doppler
- Marble Fade
- Fade
- Crimson Web (web placement varies by pattern)
- Slaughter (color region distribution)
Practical takeaways
- Pattern index is a uniform 0–999 roll, independent of float and rarity.
- Pattern matters dramatically on Case Hardened, Doppler, Marble Fade, and Fade — and almost not at all on most other finishes.
- Tier-1 Case Hardened patterns trade at 5–10× Tier-2 prices on the same float; Marble Fade FFI carries a similar premium.
- Pattern indices are weapon-specific — never assume cross-weapon equivalence.
- Verify pattern claims with established community pattern databases before committing to a high-value transaction.
Pattern index is the most under-appreciated dimension in CS2 skin valuation by casual players and the most rigorously tracked dimension by serious collectors. Any skin in the pattern-sensitive families should be evaluated for pattern tier before any other valuation step, because the pattern can override every other factor — a Tier-1 pattern on a Battle-Scarred skin can be worth more than a standard pattern on a Factory New of the same finish, by an order of magnitude.
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