Short answer
Omega does not build an Aqua Terra with 300 m of water resistance. The Aqua Terra line is rated at 150 m (15 bar). The 300 m rating belongs to the Seamaster Diver 300M, a separate model with a helium escape valve at 10 o'clock, a ceramic bezel insert and a wave-pattern dial. A watch sold as a "fake Omega Aqua Terra 300m 41mm" is a replica Aqua Terra with a wrong spec sheet, or a replica Diver 300M listed under the wrong name. Compare the case against the 41 mm Aqua Terra numbers below before you pay.
Genuine 41 mm Aqua Terra specs
- Case: stainless steel, 41.0 mm across, 13.2 mm thick, 20 mm lugs
- Water resistance: 150 m / 15 bar
- Crystal: domed sapphire, anti-reflective coating on both faces
- Caseback: sapphire display window
- Dial: teak deck pattern with horizontal lines, date at 6 o'clock
- Hands and indices: white gold with Super-LumiNova fill
- Movement: Caliber 8900, co-axial escapement, 39 jewels, 25,200 vph, 60 hours of power reserve, silicon balance spring, 15,000 gauss magnetic resistance
- Certification: Master Chronometer, tested by METAS, 0/+5 seconds per day
- Reference example: 220.10.41.21.01.001
These figures cover the steel 41 mm references with Caliber 8900. Gold cases and small-seconds versions use other calibers.
Tells on the case
Caseback engraving on genuine watches is cut deep with crisp letter edges. Replica engraving looks shallow and rounds off at the ends of the letters. The caseback serial and the serial on the movement bridge match on a genuine watch. On replicas they do not. Lugs on the 41 mm case measure 20 mm at the spring bar. Replica lug widths run 20.5 mm or 21 mm, which shows up when a genuine strap will not fit.
Dial, hands, and date
The teak lines on a genuine dial sit at even spacing and end at a clean edge near the rehaut. Replica dial printing uses a softer font for "OMEGA" and "CO-AXIAL MASTER CHRONOMETER", and the text sits lower on the dial. The date window at 6 o'clock is beveled on the genuine dial. Replica windows have a square edge and thicker date numerals. Hands on the genuine watch are white gold with an even lume fill. Replica hands show a bright nickel tone and lume that does not match the indices.
Movement and paperwork
Caliber 8900 has a co-axial escapement and a free-sprung balance with a silicon hairspring. Most replicas use an ETA 2824 clone or a Seagull ST2130 with a decorative plate and a printed rotor. A watchmaker can see the difference in under a minute with the caseback open. Omega ships each Master Chronometer with a card that lists the movement serial and eight METAS test results. Replicas include a printed card. The serial on that card does not appear in the METAS database.
Checks in hand
- Measure the case with calipers. 41.0 mm, not 42 mm.
- Read the water rating on the caseback. 150 m, not 300 m.
- Compare the caseback serial with the movement serial.
- Ask for the Master Chronometer card and the eight test results.
- Have a watchmaker confirm the co-axial escapement.
Unknowns
Replica makers change parts between batches. Two watches with the same listing name can hold different movements, dials and bracelets. No single check settles the question. Used prices for genuine 41 mm Aqua Terras vary by reference and condition, so check completed sales before you buy. Buy from a seller who allows a return window and an inspection by an independent watchmaker.