This is a 1940s International Watch Company “Mark 10,” featuring a highly sought-after tropical brown dial. It is the IWC model from the “Dirty Dozen,” adopted by the British Army during World War II.
It is a celebrated piece equipped with IWC’s renowned Cal.83 movement, housed in the “Hermet”—a highly airtight snap-back waterproof case used by IWC at the time—and fitted with a highly legible black luminous dial. These elements give it both the rugged practicality expected of military specifications and the exceptional quality characteristic of IWC. The dial’s brown aging further enhances its military aesthetic.
Although the print shows deterioration, the luminous material has been restored, and the case has been polished, it remains an excellent value compared with current market prices (from around ¥1.2 million).