The most interesting feature on this Submariner 6536-1 is the "Tropical" or "Color Change" dial. Although the materials and manufacturing process were the same for normal black dials, in this rare instance, the black galvanic layer has lost some of its pigment. The loss of opacity allows the underlying brass plate to show through, causing the dial to turn a brown color. This phenomena is uncommon and unique in each instance, and therefore no two Tropical dials are exactly the same. The clear lacquer layer yellows with age which gives the lettering and graphics a gold-copper tone.

 Although theories abound, the cause and length of time it takes for a Tropical dial to develop are still largely a mystery.

Case No. 398,639

The luminous material on the dial and hands was manually applied Radium like most Small Crowns from the 1950s. Although it no longer glows in the dark, the Radium still has a distinct "speckled" glow when exposed to UV Light and has a relatively high Geiger reading as well. Please see the "Luminous" section for further information about characteristics of glow-in-the-dark materials used by Rolex.

The hands are made from a metal alloy that was gold-plated. They are also flat on top, a design that came to be known by collectors as "Gilt Hands." When the hands move about the face of the dial, the sweep-seconds hand appears to lightly graze the "Chapter" ring of the minute track. When it briefly glides over the minute hand, they are perfectly aligned.

The outer case back is flat and the reference number 6536/1 is stamped inside the case back with a date code. The Submariner 6536-1 is powered by the Rolex 1030 Automatic movement. The Submariner 6536-1 and Submariner 5508 were made concurrently.