The Omega Speedmaster Reduced is a 39 mm automatic chronograph. Omega built reference 3510.50.00 from 1988 to 2009. A replica of the Reduced is judged on three things: case size, movement type, and dial layout. Size and layout you can check with calipers and a photo. Movement you have to ask about, because most copies do not use the original calibre.

Specs of the Original

  • Case: 39 mm diameter. Some listings round down to 38.5 mm.
  • Lug width: 18 mm.
  • Movement: calibre 1140. Automatic. ETA 2892-A2 base with a Dubois-Depraz chronograph module.
  • Beat rate: 28,800 vph, or 4 Hz. The running seconds hand steps 8 times per second.
  • Dial: three sub-dials at 3, 6 and 9 o'clock. Running seconds at 9 o'clock.
  • Caseback: solid steel. Ref. 3510.50.00 has no display back.

Ref. 3510.50.00 has no date window. Other Reduced references differ in crystal and dial print. Match the reference number in the listing to the watch before you compare details.

Reduced vs Professional

The Professional Moonwatch is 42 mm. It winds by hand and takes 20 mm straps. The Reduced is 39 mm, winds by rotor, and takes 18 mm straps. The pushers and crown sit at a different height on the case. Dial text differs too, so a photo of one model does not help you judge the other.

Where Replicas Deviate

  • Movement. Many copies run quartz. Quartz running seconds ticks once per second. The original steps 8 times. Some automatic copies use a Seagull ST19 or a 2824-type movement, which changes sub-dial spacing and hand stack height.
  • Case size. Copies measure 40 mm or 41 mm. Measure with calipers, not by eye.
  • Lug width. Copies often take 20 mm straps, which is the Moonwatch size.
  • Back. A display caseback on a 3510.50.00 copy is not correct for that reference.
  • Dial print. Font weight and letter spacing are the easiest tells in photos.

Checks Before You Pay

  1. Ask for the movement name and a clear photo of the movement.
  2. Ask for caliper readings of the case diameter and the lug width.
  3. Ask for a 10-second video. Watch the small seconds hand at 9 o'clock.
  4. Ask which reference the copy follows.

What Is Not Published

Replica makers do not publish movement specs, water resistance, or materials. Listings repeat numbers from the original watch. Weight and water resistance figures for the original also vary by reference and source. Treat any number that comes without a photo as unverified.