Panerai was originally a maker of precision instruments, as well as watches, but when the company set out to produce dive watches for the Italian Navy in the 1930s, it turned to Rolex for help. No watch brand at the time had yet cracked the code for water resistance, but Panerai knew that Rolex had gained a reputation for its research in the field of waterproof watches. Rolex had developed a screw-down crown, and agreed to supply Panerai with both crowns and movements. Throughout the 1940s and ’50s, Rolex continued to be the main supplier of watch movements and cases to the Officine Panerai Company, which then fitted them with its patented dials and crown guards. In 1997, Panerai reissued a replica version of these early watches, a limited edition of 60 examples with a period Rolex movement. The one pictured here was made circa 1936. “Brevettato” on the bezel means “patented.” It is stainless steel, with a Rolex movement, and will be auctioned by Antiquorum September 18 in New York.