Short answer
The Omega Speedmaster Reduced measures 39mm across the case in most reference listings. Sellers who write 38mm are rounding down. A replica of the same model also measures about 39mm, so a tape measure will not separate them. Check the movement, the date window, and the caseback engraving instead. The main reference is 3510.50.00, built from 1988 to about 2009.
Case and size
The case is steel, 39mm wide, about 12mm thick, with an 18mm lug width. The crown sits at 3 o'clock. The two pushers sit at 2 and 4 o'clock. The 3510.50.00 uses a hesalite crystal. The later 3539.50 uses sapphire. The Speedmaster Professional is a different watch: 42mm, manual wind, no date. Do not compare a Reduced to a Professional and expect the same numbers.
Movement
The Reduced runs on Omega calibre 3220. It is automatic. The base is an ETA 2892-A2 with a Dubois-Depraz chronograph module stacked on top. This matters for two reasons.
- A quartz replica is common. If the small seconds hand jumps once per second, the watch is quartz. The genuine movement beats 28,800 times per hour, so the hand moves in eight small steps per second.
- The module adds service cost. Ask for service records. A seller with no records is a seller with an unknown bill ahead.
Dial and hands
The dial has three subdials at 3, 6, and 9 o'clock. The date window sits at 3 o'clock. The Professional has no date, so a date at 3 is correct here and wrong there. Check the date wheel font and the alignment of the number inside the window. Replicas often show a thick font or a number that sits off center. Compare the dial text to catalog photos of the exact reference. Print weight, letter spacing, and the Omega symbol shape vary on replicas.
Caseback and markings
The caseback is solid steel with Omega markings. Engraving on genuine watches cuts deep and clean. Replicas show shallow cuts and soft edges. Reference and serial numbers sit on the caseback and on the movement. Ask for photos of both and confirm they match the seller's description.
Weak tests
Mass is a poor test. Bracelet link count changes the total, so a light watch may still be genuine. Case diameter is a poor test for the same reason, since both real and fake cases land near 39mm. Lume color is unreliable on older watches because tritium and Super-LumiNova age at different rates.
Buying checks
- Ask for a clear photo of the movement and the rotor.
- Ask for a photo of the caseback engraving at an angle.
- Compare dial photos to reference photos of 3510.50.00.
- Check recent sold prices. Genuine used examples trade in the low thousands of US dollars. A new watch at $120 is not one.
- Budget for service. The chronograph module is the costly part.
Some dial and bracelet variants exist across the production run. I cannot confirm every variant from memory. Verify the exact reference against Omega documentation before you pay.