The present watch is a very attractive example of a reference 1675 dating from the 1960s, preserved in very good original overall condition. It is distinguished by the rare and much sought-after black gloss "underline" dial with gilt printing. The attentive observer will notice the small silvered line underneath the designation "Officially Certified", a feature exclusively found on some Rolex GMT watches made in the early 1960s.
Black gloss dials must be regarded as the ultimate art in dial manufacturing since they reveal a rich complexity of different layers applied to the metal base. In fact, the gilt writing and minute markings are not printed on the black background but are underneath and shine through in negative relief. However to further enhance its sophistication, the silvered underline is superimposed and printed onto the black background.
Another unusual feature of the present GMT are the crown guards, narrowing from bottom to top, as opposed to the commonly found pointed crown guards found in models from the period, also nicknamed "cornino" or small horn by Italian Rolex aficionados. All later GMT cases feature the now standard rounded crown guard shoulders.
Following the success of the original GMT-Master reference 6542 in 1954, Rolex introduced successor reference 1675 only five years later. Reference 1675 stayed in production until 1980. The yellow gold version of reference 1675 originally came without crown guards, which were only introduced in 1967 on the yellow gold version to match their stainless steel counterparts. Upon its introduction, the reference was available in 18K gold or stainless steel. At the start of the 1970s, Rolex also produced versions in steel and gold, a metal combination the company markets as "Rolesor".