Corum fine 18ct gold twenty dollar coin watch, circa 1980 dial: concealed, gilt calibre: cal. Manual winding, 18 jewels movement number: 24412 case: U.S. Twenty dollar coin of 1904, hinged and sprung, glass deficient case number: 59-82, dimensions 34 mm signed: case, dial and movement accessories: none Versions of this ingenious watch were introduced in the 1930s and set a precedent for similar time pieces by master watch makers, particularly so for Corum as the coin watch became a signature marque for the brand. The masterful concealment of a watch in a hollowed-out 90% gold American U.S. Twenty dollar coin is a display of inventive horological craftsmanship at its creative and whimsical best.