The Jumelle de Nicour is a 19th-century French detective camera made by Geymet & Alker, styled in the form of a binocular (jumelle) to disguise its purpose. It is a wet/dry-plate era apparatus aimed at discreet street use rather than studio work, and survives today almost exclusively in collector and museum hands.

With only a single recorded UK auction hammer result in our dataset — £37,000 in November 2015 — there is no meaningful range to quote, and as of 2026 the model trades in five-figure territory at saleroom level rather than at retail. A piece this scarce sells for whatever two determined collectors are willing to bid on the day, so the price any given example is worth can vary widely from this benchmark depending on completeness and provenance.