For all the Rolex Datejust's versatility--for its ability to be dressed up or down, for the fact that it looks killer or a NATO, a Jubilee, a leather strap, or even in --it doesn't come across as a decidedly sporty watch. Compared with the flash of the or the robustness of the , the Datejust can seem like a quieter, more staid choice. It's the ultimate go-anywhere, do anything-watch, to be sure, but if you're looking for a the sporty feel of the classic Rolex Oyster, the Datejust likely isn't going to be it.

And then, there's the Turn-O-Graph. 

Introduced in 1953, the Turn-O-Graph is a contemporary of the Submariner, and earlier iterations (Reference 6202) resembled a Submariner but for the bezel, which had what Rolex dubbed a "time-recording rim," used to measure elapsed time. These early Turn-O-Graphs also featured textured dials, which Rolex called "honeycomb" dials, and in the mid-1950s gained the Mercedes hands so typical of Submariners. Rolex marketed the Turn-O-Graph to business travelers until the debut of the GMT Master in 1954. 

The purpose of the Turn-O-Graph was to provide consumers with a less expensive alternative to chronographs, which cost more than time-only watches; also, it saved Rolex the need to develop a waterproof chronograph (the Daytona being a decade or so from existence). 

In 1956, Rolex conceived of a new variant of Turn-O-Graph to honor the Thunderbirds, a U.S. Air Force squadron devoted to aerial demonstrations. Rolex built this new model (Reference 6609) upon the bones of the Datejust (the 36mm Oyster Case), but with an 18k gold case and the rotating bezel. Rolex offered the new reference of Turn-O-Graph to the Thunderbirds, thus giving it the nickname by which it is best known in the States.

Rolex discontinued the Reference 6609 in 1959, replacing it with the Reference 1625. The 1625, which ran from 1959 to 1977, was offered in two variants--two-tone steel and yellow gold like the Reference 6609, or steel with a white gold bezel. Unlike the Datejust, the Turn-O-Graph was never offered entirely in steel. 

This particular Turn-O-Graph, a reference 1625, sports a stunning silver dial and Jubilee bracelet giving it a touch of elegance while the trademark rotating bezel offers a sporty flair. A relative rarity on the market, the Reference 1625 Turn-O-Graph remains highly-collectible, a seldom-seen alternative to the Datejust that's sure to fly away soon--snag it before it does.