{"reference": {"slug": "greubel-forsey-ip1", "brand": "Greubel Forsey", "ref": "IP1", "model": "Invention Piece 1", "case_material": "18k Pink Gold", "provenance": "extracted_from_auction_comps", "url": "https://mostexpensivewatches.net/reference/greubel-forsey-ip1", "description": "The Greubel Forsey Invention Piece 1 (IP1) was introduced in 2007 as a limited edition of 33 pieces, with 11 units produced in 18k pink gold. This reference commemorates the Double Tourbillon 30°, the brand’s first fundamental invention. The caliber features two tourbillon cages, one rotating every sixty seconds at a 30-degree angle inside a second cage rotating every four minutes. The dial layout omits traditional hands, utilizing two concentric rotating disks for hours and minutes positioned over a large frosted bridge. Collectors value the IP1 for its historical significance as the first entry in the Invention Piece series and its architectural movement finishing. On the secondary market, this reference typically trades in the mid-to-high six-figure range. A notable auction result occurred in 2021 when a pink gold example sold for approximately $475,000, reflecting its rarity compared to the platinum and white gold variants."}, "listing_stats": {"count": 0, "median": 0, "low": 0, "high": 0}, "listings": [], "auction_lots": [{"slug": "greubel-forsey-invention-piece-1", "brand": "Greubel Forsey", "reference": "IP1", "model": "Invention Piece 1", "case_material": "18k Pink Gold", "hammer_usd": 400000, "year_sold": 2021, "venue": "Christie's Hong Kong", "lot_summary": "A tribute to the Double Tourbillon 30°, this piece displays time via two rotating disks. It represents the brand's commitment to reinventing the tourbillon for the wristwatch era.", "url": "https://mostexpensivewatches.net/auctions/greubel-forsey-invention-piece-1"}]}