A company like Rolex, which has seen its 100th birthday come and go, has celebrated quite a few milestones along the way. So it is only logical that from time to time (no pun intended) the firm manufactures special "anniversary" models to pay tribute to some of its famous watches that have become part of a popular lore.

The Rolex Datejust, for example, was the first watch with date window display and it became a model that generations of later watches would pattern themselves after. Created in 1945 as part of the Oyster Perpetual Line, the DateJust celebrated its 45th birthday in 1990. To mark this occasion, Rolex produced a gent's anniversary edition model that featured, appropriately enough, an 18-carat yellow gold and steel Jubilee bracelet, and a gold Jubilee dial set with diamond hour markers. What a dazzling way to ease into mid-life crisis!

Mid-1950s saw the birth of two models that would become some of Rolex's most prized sports watches in its Oyster Professional collection. The Submariner, which rose (or should I say "plunged") to fame with the amphibious secret agent James Bond, was created in 1953 and launched the following year. Rolex commemorated the half-century mark by introducing the 50th anniversary model with a black dial surrounded by a green rotatable bezel. Why green? Because that is Rolex's corporate colour.

Green also features prominently on another "baby boomer," the GMT-Master (GMT stands for "Greenwich Mean Time"). Created in 1955 for Pan-Am pilots on transatlantic flights, this "aviator's" watch subsequently gained popularity with NASA astronauts, including Jack Swigert, who wore it on the troubled Apollo 13 mission.

The anniversary GMT-Master has a green dial with a gold second hour hand pointing to the time in a second time zone on a rotatable black 24-hour bezel.

All the anniversary models have become hot collectors' items. They are a fine reminder that longevity has nothing to do with age.