Direct answer: As of late 2025, the most expensive CS-related skin on record is the Karambit Case Hardened (Blue Gem) with Pattern 387, commonly cited at about $1.5 million USD and sometimes reported approaching $2 million in private sales or bids. The next-tier ultra-rare item often referenced is the AK-47 Case Hardened (Blue Gem) Pattern 661, with public sales notes in the hundreds of thousands to over a million in some extreme cases. Note that market prices for CS2/CS:GO skins are highly volatile and depend on wear, pattern, float, provenance, and the presence of verified sale records, so individual valuations can change quickly and may be subject to seller disclosures or auction terms. If you’re evaluating current values, check trusted marketplaces and recent sale records for the exact pattern and condition. Context and key points

• Latest consensus: Karambit | Case Hardened (Blue Gem) with Pattern 387 is the single most expensive CS skin ever publicly documented, with reported values around $1.5 million USD and occasional headlines noting even higher figures in private deals. This reflects extreme rarity of the Blue Gem pattern across this knife and its long-standing desirability among collectors. [source-based awareness, widely reported in 2024–2025 trade coverage]
• Extremely rare variant: AK-47 | Case Hardened, Pattern 661 (Blue Gem) is often cited as one of the most valuable CS skin records, including a publicly documented sale approaching or surpassing seven figures in some years, depending on condition and authentication. This pattern is exceptionally scarce, contributing to its high value. [trading-community summaries and market reports]
• Market dynamics: The CS2/CS:GO skin market prices are influenced by rarity, drop history, float values, condition (Factory New, Minimal Wear, etc.), provenance (notable auctions, celebrity sales), and fever among collectors. High-profile sales frequently drive subsequent bids and perceived value, but prices can be volatile and not guaranteed in every transaction. [market analysis summaries]
• Notable references: Several industry recap pieces and market trackers in 2024–2025 consistently name the Blue Gem Karambit as the top-record skin and note the AK-47 Case Hardened Blue Gem as among the rarest and most expensive, with documented single-item sales and high-end auction activity. [market roundups and trade sites]

If you’d like, I can pull up the latest public sale records and summarize the current asking prices and highest confirmed sale prices from trusted marketplaces and auction posts, then present a concise ranked list of the top CS skins by confirmed sale value.