Blue Gems in CS2: Case Hardened Patterns Explained

A blue gem is a Case Hardened skin whose pattern puts mostly blue steel on the visible side. Case Hardened is a metal finish with blue, gold and purple patches, and the layout of those patches is set by the skin's pattern number (paint seed, 0–1000). Most patterns are a mix; a handful are almost all blue, and those "blue gems" sell for many times the normal price.

How blue gems work

• Pattern, not float, decides it. Every Case Hardened skin has a pattern number from 0 to 1000, fixed when the item is created.
• Each weapon has its own best patterns. A seed that is blue on an AK-47 is not blue on a Karambit.
• Tiers. Collectors rank patterns into tiers by how much blue shows, and on which side of the weapon (the "playside" facing you in game matters most).
• Float matters less. Worn blue gems still sell high; low float is a bonus.

Famous blue gems

• AK-47 | Case Hardened pattern #661 is the best-known blue gem in the game and one of the most expensive skins ever sold.
• Karambit | Case Hardened pattern #387 is the most famous knife blue gem. See the Karambit guide.
• Five-SeveN, MAC-10 and other knife blue gems are cheaper entry points for collectors.

For the most expensive items overall, see most expensive CS2 skins and most expensive knives.

Case Hardened knives (20)

Every knife with an original finish set can roll Case Hardened, so every one of these has its own blue gem patterns:

BayonetCase Hardened

Butterfly KnifeCase Hardened

Survival KnifeCase Hardened

Paracord KnifeCase Hardened

Classic KnifeCase Hardened

Falchion KnifeCase Hardened

Flip KnifeCase Hardened

Gut KnifeCase Hardened

Navaja KnifeCase Hardened

KarambitCase HardenedKukri KnifeCase HardenedM9 BayonetCase Hardened

Nomad KnifeCase Hardened

Shadow DaggersCase Hardened

Skeleton KnifeCase Hardened

Stiletto KnifeCase Hardened

Bowie KnifeCase Hardened

Huntsman KnifeCase Hardened

Ursus KnifeCase Hardened

Talon KnifeCase Hardened

Case Hardened guns (4)

Case HardenedClutch Case
Float 0.06–0.80

Case HardenedCS:GO Weapon Case
Float 0.00–1.00 · StatTrakCase HardenedCS:GO Weapon Case 2
Float 0.00–1.00 · StatTrakCase Hardened2021 Dust 2 Collection
Float 0.00–1.00

Blue gem tiers

Tier lists are made by the community, so two sellers can rank the same seed differently. Always look at the skin yourself.

Playside vs backside

The playside is the side you see in first person. A skin that is blue on the playside is worth far more than one that is blue only on the back. On knives, collectors also look at the blade tip and the spine separately.

Gold gems and Heat Treated

Some collectors look for the opposite: gold gems, patterns that are almost all gold. The newer Heat Treated finish (Desert Eagle | Heat Treated, Five-SeveN | Heat Treated) uses a similar heat-coloured metal look, and its patterns are starting to be collected the same way.

How to check a pattern

1. Inspect the skin in game or on the Steam market; the pattern number is shown in the inspect view and on most trading sites.
2. Compare the number with a pattern database or screenshots of the same seed, and look at both sides of the weapon.
3. Be careful with "blue gem" claims in listings: check the playside with your own eyes before paying a premium.

Can you get a blue gem from a trade-up?

Yes, in theory: a Case Hardened knife or gun from a trade-up gets a random pattern like any other drop. The chance of hitting a top blue gem is tiny, so don't plan on it. Price the contract honestly in the knife trade-up calculator.

Frequently asked questions