ROLEX GMT Master 1675 “OCC TROPICAL DIAL” 1960s

Introduced in 1954, the GMT-Master made its debut with the first-generation Ref. 6542, powered by the Caliber 1035.

Soon afterward, the non-chronometer Caliber 1535 was developed, and in 1960 the Ref. 1675 was introduced with a chronometer-certified version of the 1535, adjusted in five positions.

The evolution of the Ref. 1675 is largely defined by its dial variations.

The earliest examples featured glossy gilt dials with an outer chapter ring, commonly classified as Mark 0 through Mark 3. Around 1963, the chapter ring was removed while retaining the gilt finish, producing another series of Mark 1 through Mark 3 dials. By approximately 1966, the model transitioned to matte dials, evolving through Mark 1 to Mark 7.

Among all of these, the most significant is the OCC dial—known as the Mark 0.

Equipped with a regulator that allowed simplified time adjustment, it represents the earliest and most distinctive configuration of the Ref. 1675.

Rolex later eliminated the regulator system, improving resistance to shock and vibration while enhancing overall stability. This evolution led to the introduction of the SCOC configuration, distinguished by the addition of the word “SUPERLATIVE” on the dial.

The OCC dial, however, had only a brief production life.

Its production concluded during the second manufacturing period of 1960, within the serial range beginning around 5032 to 505, making surviving examples exceptionally scarce.

A glossy gilt dial with smaller hour markers.

A 24-hour hand extending slightly beyond the chapter ring.

The Caliber 1565, fitted with the distinctive “butterfly rotor,” together with a hairspring anti-entanglement design, regulator system, and an 18,000-vph low-beat rhythm.

Together, these elements define the legendary OCC dial—an enduring symbol of the earliest chapter in the history of the GMT-Master Ref. 1675.