Most people who are interested in Rolex collections have a good understanding of their legendary, multi-time zone pilot’s watch, the GMT-Master. Even though the various GMT-Master and GMT-Master II references with their soda-themed nicknames have become mainstays within the luxury collecting world, there is an extra iteration that gains far less focus: the Rolex Blueberry GMT. 
The “Blueberry” GMT-Master is necessarily just a regular reference 1675 from the 1970s that was originally fitted with an all-blue bezel insert. Different from the other colors of bezel inserts that have been available for the GMT-Master line of watches, the all-blue insert of the “Blueberry” GMT is not something that Rolex replica ever officially provided as an option at any of their regular authorized dealers.
On the contrary, the blue, GMT bezel insert was made in small numbers during the 1970s, and reserved exclusively for particular orders by select retailers and military groups – examples can be found with the UAE Air Force emblem on the dial. Exact production numbers are unknown; however since the all-blue, GMT bezel insert was never officially provided to the general public, even service replacement inserts would have existed in significantly smaller numbers than the rest of the available colors.
A very small number of the “Blueberry” GMT-Master replica watches in existence were originally fitted with their all-blue bezel inserts. Lots of reproduction “Blueberry” GMT inserts are available today; however, a huge number of the genuine all-blue inserts are not actually original to their respective watches, but rather added on later during a subsequent service or repair.
The era of fake Rolex dials pre-dates the whole window of time in which these all-blue bezel inserts were in production. As a result, all “Blueberry” GMT-Master watches will be fitted with matte dials with white text, instead of the earlier glossy gilt dials, or later era gloss dials with white gold surround for the hour markers. What’s more, the “Blueberry” GMT-Master can be found with either an all-red GMT-hand or the classic GMT-hand with the red center section; however, it should be noted that the all-red GMT-hand variant is generally considered to be less common.
Since the all-blue bezel insert is the only defining feature of the “Blueberry” GMT-Master, the price and desirability of such inserts have gone up crazily in recent years, as an increasing number of buyers have tried to secure one for their own collections.