Two Karambit knives in Counter-Strike 2 can have the same finish, the same wear and the same name. One sells for about $600. The owner of the other turned down an offer of more than a million.
The difference is a number between 0 and 1000 that most players never look at. It's called the paint seed, and on one finish, Case Hardened, it decides almost everything about the price.
What is a blue gem?
A blue gem is a Case Hardened skin whose pattern shows almost only blue on the side you see in game.
Case Hardened is one large texture of blue, purple and gold stains. Every item gets a paint seed from 0 to 1000, and the seed picks which slice of that texture is painted on. Most seeds give a mix with plenty of gold and purple. A handful put a near-solid sheet of blue on the visible side, which players call the play side. Those are the blue gems.
Three things are worth knowing:
- The seed never changes. A blue gem stays a blue gem at any wear, for as long as the item exists.
- Pattern and float are different things. Float decides how worn the skin looks. The seed decides where the colours sit.
- It isn't one skin. Case Hardened comes on 23 items: the AK-47, the Five-SeveN, the MAC-10 and 20 knife types. Each has its own list of blue gem seeds.
The rankings are made by the community, not by Valve. Collectors sort the seeds into tiers by how much blue lands on the play side. For the Karambit, the usual ranking has 10 tier 1 seeds, with #387 at the top. You can see the full Karambit blue gem tier list on cs2tradeup.gg, along with tier lists for every Case Hardened item.
Which blue gems are the most famous?
Two items carry most of the legend.
The Karambit #387. A Factory New Karambit Case Hardened with seed 387 is widely called the best blue gem in the game. In 2021, streamer ohnePixel passed its owner an offer of roughly 1.2 million, paid in Bitcoin. The owner said it was too low. Reports differ on whether the figure was in euros or dollars, and later coverage often quotes about $1.5 million. Either way, the knife has never been sold publicly.
The AK-47 #661. In June 2024, a StatTrak Factory New AK-47 Case Hardened with seed 661 sold for more than $1 million, according to the traders who brokered the deal. The exact price was not disclosed.
The same AK-47 with an ordinary seed is just another rifle skin.
How much does a blue gem cost?
There is no price tag, and that is the honest answer for the top tier.
A regular Karambit Case Hardened has a market price. On November 10, 2026, the lowest marketplace listings ran from about $575 in Battle-Scarred to about $1,485 in Factory New, according to cs2tradeup.gg. Blue gems sell above that, and the gap depends on the tier.
- Tier 1 seeds change hands in private deals between collectors. There is no public market price for them.
- Tier 2 seeds sell for a multiple of the regular price.
- Tier 3 and 4 seeds carry a smaller premium that depends on how the blue sits on the play side.
Three more things move the price: a lower float, StatTrak, and whether the blue is on the play side or only on the back.
Can you craft or unbox a specific blue gem?
Not on purpose. The seed is rolled at random every time an item is created, whether it comes from a case or from a trade-up contract. With seeds running from 0 to 1000, the chance of any one seed is roughly 1 in 1,000.
Since October 2025, five Covert skins can be traded up into a knife in CS2. That made knives easier to get. It did nothing for blue gems, because nobody can choose the seed. They are found, not made.
How do you check a blue gem before buying one?
The label "blue gem" in a listing title proves nothing. Four checks protect you.
- Read the seed yourself. Ask for the inspect link and look up the paint seed in a float checker before you pay. A seller's screenshot is not proof.
- Look at the play side. Two seeds in the same tier can look very different in hand. Ask to see the side that shows in game, not only the back.
- Compare the same seed. Check recent listings for that exact pattern, not the regular price of the skin.
- Keep the deal on a marketplace or a Steam trade. Requests to move to another chat, middlemen you didn't choose and links asking you to log in to Steam are the usual scams.
FAQ
What is the best blue gem in CS2? The Factory New Karambit Case Hardened with seed 387 is the one most collectors name. Its owner declined an offer of more than a million in 2021, and it has never been sold publicly.
Are blue gems only Case Hardened? Yes, the term is used for Case Hardened. Other pattern-based finishes have their own names, such as Doppler phases and Fade percentages.
Does wear change the pattern? No. The seed is fixed, so the pattern is the same at any float. A worn blue gem just looks more scratched.
Which AK-47 seed is the blue gem? Seed 661 is the famous one. The community ranking also puts a few other seeds in its top tier, listed on the AK-47 blue gem page.
How do I find my own pattern seed? Inspect the item in game, or paste its inspect link into a float checker. The paint seed is shown next to the float.