The company was founded in Lüdenscheid, North Rhine-Westphalia, western Germany in 1863 and moved to the Gartenstraße address in 1902.
Wilhelm Deumer's son Hugo remained childless, so the company was taken over by Wilhelm Conze in 1905. Conze introduced cufflinks, money clips, and tiepins to the company.
After the Second World War, the company supplied awards to the British Army of the Rhine.
In the 1960s, Gottfried Conze took over and was eventually succeeded by his son Johann, who now owns the family business in its 6th generation, together with his business partner Friedrich Assmann. Since the 1990s, the Deumer company has produced the lid emblem for Porsche cars.
This maker currently has no products.