The genuine Omega Seamaster Aqua Terra 150M 38mm uses a Master Chronometer Calibre 8800 inside a 38 mm steel case. Copies sell at $80, $300, and $600. Four checks catch most of them: case thickness, date window position, balance wheel type, and caseback material.
Genuine specs to memorize
- Case: 38 mm across, about 12.3 mm thick, 19 mm lug width.
- Water resistance: 150 m / 500 ft.
- Movement: Omega Co-Axial Master Chronometer Calibre 8800, automatic.
- Power reserve: 55 hours. Frequency: 25,200 vph (3.5 Hz).
- Magnetic resistance: 15,000 gauss. Certification by METAS, not by Omega alone.
- Crystal: domed sapphire.
- Caseback: sapphire display back. Crown: conical, screw-in, signed with the Omega symbol.
- Bracelet: steel, solid links, signed butterfly clasp.
Dial and hands
The date sits at 6 o'clock in a framed window. The teak pattern on the dial runs horizontal on current 38 mm references. The OMEGA logo is applied metal. Hour markers are applied. Hands are rhodium plated with white lume. Printed text sits under the logo in two lines.
Copies move the date to 3 o'clock on lower grade builds. Date font on copies is wider, and the window has no bevel. Copy dials print text with a heavier stroke and place markers a fraction off center.
Movement check
The Calibre 8800 uses a free sprung balance with a silicon hairspring. The balance bridge has no regulator arm. A watchmaker sees this through the caseback in seconds. Common copy movements are the Miyota 9015 at 28,800 vph, the Seagull ST2130, and 21,600 vph Chinese automatics. Genuine watches beat 25,200 vph. A timegrapher trace of a copy shows the wrong rate, a wobbly line, or high beat error.
Caseback and markings
Genuine watches show a decorated movement through sapphire. The rotor and bridges carry Geneva wave finishing. Serial numbers are laser engraved on the movement and stamped on the case. Copies ship with a printed rotor, a solid steel back, or a sapphire back over a plain movement with no finishing.
Bracelet and clasp
Copy bracelets use hollow end links, sharp edges, and a clasp with a stamped logo instead of a cut one. End link fit at the lugs is the easiest tell. Weight is a weak check, because copy cases run thick. Case thickness is a strong check.
Papers and certification
Master Chronometer watches come with a certification card. METAS tests eight criteria, including exposure to 15,000 gauss and a daily rate of 0 to +5 seconds. A copy does not pass this test. Sellers of copies print cards, but the number on the card does not match a certification record.
US legal note
Trafficking in counterfeit goods is a federal crime under 18 U.S.C. 2320. A first offense carries up to 10 years in prison. Civil damages under the Lanham Act reach $2,000,000 per counterfeit mark for willful use. US Customs and Border Protection can seize counterfeit watches at the border. Seizure applies to single pieces ordered for personal use.
Check order
- Measure the case across the 9 to 3 line, crown excluded.
- Look at the date window position and frame.
- Run the watch on a timegrapher and read the rate.
- Look through the caseback at the balance bridge.
- Check the clasp stamp and the end link fit.