Serial Number Range: 51xxxxx-55xxxxx
General Notes: This dial is used both on the steel and gold cased 1675/3 and gold 1675/8 during the 1970s. It continues to use the matted, grainy surface first introduced on the Mark 2 brown dial.
Distinguishing Characteristics: The Mark 4 brown dial is distinguished from the other matte easiest by looking at the spacing of the “T SWISS T.” On the Mark 4 brown dial, the Ts are wide and split the 28-29 and 31-32 indices evenly, whereas on the Mark 2 and 3 brown dials, the Ts are close to the 29 and 31 indices. The spacing of the Ts on the Mark 4 and 5 brown dials are similar but the Mark 5 has the characteristic soliel gloss finish that is very different from the matte dial. The SWISS designation on the Mark 4 also has the “I” replaced by the 30 minute index, while on the Mark 5 the “I” is visible as a separate letter printed to the right of the index.