Introduced in 1967, the Rolex Sea-Dweller was developed as a professional diving instrument, designed to withstand the demanding conditions of saturation diving. Equipped with a helium escape valve, the model became an important milestone in the development of professional diving watches.

During the late 1970s, Rolex replaced the celebrated "Double Red" Sea-Dweller with a new dial configuration featuring entirely white printing, subsequently earning the nickname "Great White" among collectors.

Of the four principal production dial variations, the Mark II, commonly referred to as the "Rail Dial", is considered the rarest and among the most desirable. Produced for a relatively short period around 1978–1979 by Stern Frères, the same dial manufacturer responsible for certain Rolex COMEX dials, this particular variation has become highly sought-after by vintage Rolex enthusiasts.

The distinctive "Rail Dial" designation refers to the precise vertical alignment of the spaces separating the words "SUPERLATIVE CHRONOMETER" and "OFFICIALLY CERTIFIED", creating two parallel lines reminiscent of railway tracks. Additional distinguishing characteristics include the elongated minute markers and the unusual "T SWISS T <25" inscription at six o'clock.

The present dial displays these characteristic features and bears the reverse marking "G7-R943", a documented signature associated with Stern-manufactured Rail Dials.

The Mark II "Rail Dial" is generally associated with Rolex Sea-Dweller reference 1665 watches bearing case serial numbers in the approximate range of 5.7 to 6.2 million, dating to circa 1978–1979.