The Case Hardened Pattern Index Explained: What's a Blue Gem in CS2?

The Case Hardened is the most pattern-sensitive skin family in CS2. The same skin in the same wear tier can trade at $300 or $300,000 depending entirely on its pattern index — a number assigned at random when the skin is generated that determines how much blue, gold, and purple appears on the weapon's surface. "Blue gem" Case Hardened items are the holy grail of CS2 collecting, and understanding the pattern system is the difference between recognizing a five-figure opportunity and overpaying for a forgettable pattern.

This deep dive explains how the Case Hardened pattern system works, what blue gem tiers actually mean, the famous patterns by skin family, and how to verify a Case Hardened's value before any significant purchase.

Quick answer

Case Hardened skins have a pattern index from 0 to 1000 that determines coloring distribution — predominantly blue patterns are called "blue gems" and trade at extreme premiums. Tier-1 blue gems (highest blue coverage) command the most extreme prices, sometimes exceeding $100,000 for AK-47 and Karambit examples. Tier-2 and Tier-3 blue gems are progressively less blue but still command significant premiums over standard Case Hardened. Pattern is more important than float on Case Hardened skins; always verify pattern index before significant purchases.

What is the Case Hardened skin family?

Case Hardened is a finish style applied to several CS2 weapons and items. The visual effect mimics oil-quenched heat-treated steel — surfaces show shifting blue, gold, purple, and brown coloring based on how the finish "took" to the underlying texture template.

Items in the Case Hardened family include:

• AK-47 Case Hardened (the most famous, highest prices, deepest collector market)
• Karambit Case Hardened (knife tier, second-highest pricing)
• Five-SeveN Case Hardened (pistol tier, smaller market but pattern matters)
• Hydra Gloves Case Hardened (glove tier, unique pricing dynamics)
• Bayonet, M9 Bayonet, and other knives in Case Hardened finishes

Each item in the family has its own pattern index system, meaning a "Tier-1 blue gem" pattern index on the AK-47 isn't the same number as on the Karambit. The general principle (high blue = high value) holds across all items, but the specific patterns differ.

How does the pattern index actually work?

Every Case Hardened skin generated in CS2 receives a pattern index between 0 and 1000, randomly assigned at the moment of creation (case opening, trade-up, or item drop). The pattern index controls which area of the skin's texture template is applied to the weapon model.

The texture template is a 2D image showing the full range of Case Hardened coloring — blue regions, gold regions, purple regions, brown regions. When applied to the 3D weapon model, only a specific subsection of the template appears on each face of the weapon. The pattern index determines which subsection.

This is why patterns vary so dramatically. A pattern that pulls heavily from the blue regions of the template produces a predominantly blue weapon. A pattern that pulls from gold regions produces a gold-and-brown weapon. The same skin name, the same wear tier, but visually completely different items.

Critically, the pattern index is permanently attached to the specific skin instance. You cannot change it. Trading the skin doesn't regenerate the pattern. The pattern you get is the pattern you have for as long as you own the item.

What are blue gem tiers in CS2?

The community has organized Case Hardened patterns into informal tiers based on blue coverage and visual quality. The tier system isn't formally defined by Valve — it's community-maintained and somewhat subjective at the margins — but the general structure is widely accepted.

Tier 1 (T1) — The "true" blue gems

The most desirable patterns, with the highest blue coverage and cleanest visual appearance. For AK-47, this includes specific famous patterns by index number. Tier 1 examples command the most extreme prices in the Case Hardened market — six and sometimes seven figures for the most prized specific patterns.

Examples for AK-47 (informal community-recognized tier):

• Pattern index 661 (the most famous AK Case Hardened, often called "the 661")
• Pattern index 387
• Pattern index 670
• Several others widely recognized in the collector community

Tier 2 (T2) — High blue but with some gold or purple

Patterns where blue dominates but isn't pure. Still command significant premium over standard Case Hardened — often 10–50x the base price — but trade at meaningful discount to Tier 1.

Tier 3 (T3) — Mixed patterns leaning blue

Patterns with notable blue presence but more visible gold or purple regions. Premium pricing but more accessible than Tier 1 or 2. Often the practical "entry point" for collectors wanting a blue-leaning Case Hardened without paying T1 prices.

Mid-tier and standard patterns

Patterns with balanced coloring or predominantly gold/purple coverage. Trade at the standard Case Hardened price for the skin (which is still meaningful — a standard AK-47 Case Hardened in FN is hundreds to low thousands of dollars).

Bottom-tier patterns

Patterns dominated by less-desirable coloring — heavy brown regions, dull combinations. Trade slightly below standard Case Hardened pricing.

How do I verify a Case Hardened's pattern index?

Verifying pattern before buying is essential for any Case Hardened purchase above standard pricing.

On third-party platforms: CSFloat displays pattern index prominently on every Case Hardened listing. Skinport and SkinSwap also surface pattern data. The pattern index number lets you cross-reference against community pattern databases.

On Steam Community Market: Steam doesn't display pattern natively. To check:

1. Click the listing to view the item.
2. Use Steam's inspect-in-game feature to view the actual visual appearance.
3. For a precise pattern index number, install a browser extension like CSFloat's that surfaces pattern index on Steam listings.
4. Cross-reference the pattern index against community databases to see where it falls in the tier hierarchy.

Community pattern databases: several community-maintained resources catalog famous and notable Case Hardened patterns by index number. Pattern databases for AK-47, Karambit, Five-SeveN, and other Case Hardened items document which indexes produce which visual results. Before any high-value Case Hardened purchase, cross-referencing the listing's pattern index against these databases is standard practice.

What are the famous Case Hardened patterns by skin?

AK-47 Case Hardened patterns

The AK-47 Case Hardened pattern market is the deepest and most studied. Several specific pattern indexes are famous in the collector community:

• Pattern 661: the most famous AK-47 Case Hardened pattern. Heavy blue coverage with minimal gold or purple interference. Historic trades on this pattern are among the most-cited in CS skin history.
• Pattern 387: another Tier 1 contender, with strong blue coverage and cleaner aesthetics.
• Pattern 670: recognized Tier 1 pattern.
• Several other named patterns recognized by AK-specific collector communities.

Karambit Case Hardened patterns

The Karambit Case Hardened pattern system has its own tier hierarchy, with different specific indexes than the AK. Pure blue patterns on Karambit Case Hardened (Tier 1) command some of the highest knife prices in CS2 — five and six-figure examples exist in the collector market.

Five-SeveN Case Hardened patterns

Smaller market than AK or Karambit but the pattern system still drives meaningful pricing variation. Tier 1 Five-SeveN Case Hardened patterns trade at significant premium over standard examples, though absolute dollar amounts are lower than the AK or Karambit equivalents.

Hydra Gloves Case Hardened patterns

Gloves have their own pattern dynamics. Hydra Gloves Case Hardened with heavy blue coverage command notable premium, though the glove market has different liquidity characteristics than weapons or knives.

For any of these items, the specific pattern index is what drives pricing — verify before buying.

How does float interact with pattern on Case Hardened?

Pattern dominates pricing on Case Hardened, but float still matters. For Tier 1 and Tier 2 blue gems, low-float Factory New examples command additional premium over standard Factory New floats. The ideal Case Hardened collectible is a Tier 1 pattern at sub-0.01 float in Factory New — extreme rarity that intersects two desirable variables simultaneously.

For lower pattern tiers, float matters less because the pattern is already the primary value driver. A mid-tier pattern Case Hardened in Field-Tested often trades within 20–30% of the same pattern in Factory New, because pattern is doing the pricing work.

The practical hierarchy of variables on Case Hardened: pattern tier first, float second, stickers third. Always verify in that order.

Where should I buy a Case Hardened CS2 skin?

For pattern-sensitive purchases, the platform matters significantly.

For high-tier Case Hardened (T1 or T2 blue gems): BUFF163 has the deepest global inventory and the most expert seller base for verifying pattern claims. CSFloat is the strongest Western alternative, with prominent pattern display and active collector community. Direct collector-to-collector negotiation through verified middlemen is also common at the top end.

For mid-tier Case Hardened (T3 patterns or attractive standard patterns): Skinport, CSFloat, and SkinSwap all have inventory. CSFloat is still the strongest single platform for pattern-focused buyers because the platform surfaces pattern index on every listing automatically.

For trade-in scenarios: SkinSwap or Tradeit.gg let you trade existing CS2 inventory for Case Hardened items from platform inventory directly. Useful for consolidating mid-tier skins into a single Case Hardened item, though the bot pricing typically reflects standard pattern pricing rather than premium pattern recognition.

For any Case Hardened purchase above $1,000, the verification flow is: confirm the pattern index, cross-reference against community pattern databases, verify the float, verify any applied stickers, cross-check pricing across at least two platforms, then commit. Five to ten minutes of verification can swing the value of a single purchase by tens of thousands of dollars at the top end.

Sources

• CSFloat — Pattern Search and Database for Case Hardened
• Steam Community Market — AK-47 Case Hardened Listings
• Skinport — Case Hardened P2P Marketplace
• BUFF Market — Global Case Hardened Pricing Reference
• SkinSwap — Case Hardened Trading and Buying
• Counter-Strike Official Website
• r/GlobalOffensive — Community Pattern Discussion