Case Hardened and Blue Gem Patterns
What Case Hardened Is
Case Hardened mimics heat-treated steel, with patches of blue, gold and purple scattered across the surface. The placement of those colours is set by the paint seed, so every copy is different.
Most copies are dominated by gold with limited blue. The rare copies with large areas of blue, especially on the most visible surface, are what collectors call blue gems.
What Makes a Blue Gem
A blue gem is a Case Hardened copy with unusually high blue coverage on the playside, the face of the weapon you see in game. The more blue, and the more concentrated it is on that side, the more desirable the copy.
Backside blue matters less, since you rarely see it. This is why two copies with similar overall blue can be valued very differently.
Famous Pattern Seeds
On the AK-47 Case Hardened, seed 661 is the most famous blue gem, with other seeds such as 670, 955 and 179 also ranking highly. Each weapon that has Case Hardened has its own tier list of top seeds, maintained by the community.
These rankings are informal but widely followed, and top seeds on popular weapons can trade at enormous premiums over a plain copy.
How to Check a Pattern
Steam shows the paint seed only indirectly, so collectors use third-party pattern checkers that cross-reference the seed against known tier lists. Always confirm the seed with the inspect link before paying a blue-gem premium.
Our inspect link guide shows how to view the exact item.
Buying a Case Hardened
Decide whether you want a specific tier seed or simply a copy you like the look of. If you are not chasing a known blue gem, you can often find an attractive copy for far less by judging it by eye.
For more finishes where the pattern drives value, see our top pattern skins guide.
How Blue Gem Values Behave
Top blue-gem seeds on popular weapons sit in a thin, specialist market where a handful of buyers compete for a handful of copies. That can make prices volatile and hard to compare, since no two copies are identical.
Reading past sales for similar seeds helps set expectations. Our price history guide explains how to interpret that data without over-reading short-term swings.
Frequently Asked Questions
What is a blue gem?
A blue gem is a Case Hardened copy with a high share of blue on its playside, the face seen in game. The more blue, and the more concentrated on that side, the more valuable the copy.
Why is seed 661 famous?
On the AK-47 Case Hardened, pattern seed 661 produces one of the most blue-dominant playsides known, making it the most celebrated blue gem seed for that weapon. Top seeds trade at large premiums.
Does backside blue count?
Much less. Because you mainly see the playside in game, blue on the back of the weapon adds little value. Collectors focus on the visible face.
How do I check a Case Hardened pattern?
Use a third-party pattern checker that reads the paint seed from the inspect link and compares it to community tier lists. Always confirm before paying a premium.
Do I have to buy a known blue gem?
No. If you simply like how a copy looks, you can often buy an attractive Case Hardened for far less than a ranked blue-gem seed. Judge by eye if you are not collecting.