Omega Speedmaster watches

The Omega Speedmaster began in 1957 as a sports and racing chronograph, the reference CK 2915, and took its name from its tachymeter bezel, following Omega's Seamaster and Railmaster. Since the Speedmaster 125 of 1973, the name has also covered a wider family, from 1970s automatics and the smaller Reduced to the digital-analog X-33 and the 44.25 mm Moonwatch Co-Axial chronographs.

The automatic Speedmaster Mark III and Mark IV arrived in 1971 and 1973. The Speedmaster Reduced came in 1988 as a smaller version, built on an Omega 3220 base movement with a Dubois Depraz chronograph module. The X-33 appeared in 1998 and flew on Mir and on the Space Shuttle mission STS-90. In 2013 Omega reissued the CK 2915 as the Speedmaster '57, with the self-winding calibre 9300, a 60-hour reserve and a 41.5 mm case; in 2015 it gained broad arrow hands. 2013 also brought the Dark Side of the Moon, with a ceramic case and a zirconium oxide ceramic dial.

Case size sorts the line. The Reduced is the 39 mm model, many with acrylic crystals; the Reduced Ladies sets mother-of-pearl dials, often with diamonds, and Michael Schumacher, an Omega ambassador, gave his name to Reduced models with yellow, red, blue and silver dials. The '57 Co-Axial is the 41.5 mm reissue, in steel, yellow and red gold and titanium, while the Date, Day-Date and Co-Axial 38 models sit between 38 and 40 mm.

The Moonwatch Co-Axial, Racing Master, Moonphase Chronograph and the Broad Arrow GMT and Rattrapante share a 44.25 mm case, as do the ceramic Dark, White and Diamond Side of the Moon models and the blue ceramic Blue Side of the Moon Moonphase. The titanium X-33 measures 42 mm and the Skywalker X-33 45 mm, and the Speedmaster 125 of 1973 is a 42 mm steel watch with an acrylic crystal.