Short answer
An Omega Seamaster 300M copy is a watch built to the outside dimensions of the Seamaster Diver 300M. The genuine watch has a 42 mm steel case, a 13.6 mm profile, 49.9 mm lug to lug, and a 300 m water resistance rating. It runs the Omega Co-Axial Master Chronometer Calibre 8800 with a 55 hour power reserve. Copies match the case shape and the dial layout. They do not use the 8800 movement. Most carry a third party automatic calibre, a 2824 pattern or a Miyota 9015 pattern. Steel grade, dial wave production, and lume are the parts that change from one copy to the next.
Genuine Seamaster Diver 300M specs
- Case: 42 mm diameter, 13.6 mm thick, stainless steel
- Helium escape valve at the 10 o'clock position
- Bezel: ceramic insert, white enamel dive scale, 60 minute count
- Dial: ceramic, laser engraved wave pattern
- Crystal: domed sapphire, anti reflective coating on the inner face
- Movement: Calibre 8800, co axial escapement, free sprung balance
- Power reserve: 55 hours
- Magnetic resistance: 15,000 gauss
- Certification: METAS Master Chronometer, 8 test series
- Water resistance: 300 m, built to ISO 6425
What copies match
Good copies hold the 42 mm case diameter and the 20 mm lug width. The bezel turns in 60 clicks and lines up with the dial markers. The helium valve sits at 10 o'clock and the crown guards sit at 3 o'clock. The crystal is sapphire on the higher tiers. Case back engraving follows the seahorse and the case reference. Bracelet taper runs from 20 mm to 18 mm at the clasp on most builds.
What copies change
Steel grade is the first difference. Genuine Omega cases use 904L. Low tier copies use 316L. 904L holds about 25 percent nickel and 4.5 percent molybdenum. 316L holds about 10 percent nickel and 2 percent molybdenum. The mix changes color under light and changes total weight.
The movement is the second difference. No copy carries an Omega 8800. Common substitutes are the Seagull ST2130, the Hangzhou 6300, and the Miyota 9015. Beat rate is 28,800 vph on all three. Power reserve runs 38 to 42 hours. Decorated plates are added to look like the 8800.
replica omega seamaster 300m watch
Dial waves are the third difference. The genuine dial is ceramic with laser cut waves. Copies use stamped metal or printed plastic on low tiers and laser cut ceramic on high tiers. Lume is the fourth difference. Genuine watches use Super-LumiNova. Copies use C3 or C1 grade pigment. Glow duration drops.
Checks before purchase
- Ask for the case diameter measured with calipers.
- Ask for the movement name and the beat rate.
- Ask for the steel grade, 316L or 904L.
- Ask for a pressure test result. Most copies ship without one.
- Weigh the watch. A 42 mm steel Seamaster on a full bracelet weighs near 195 g. Copies land between 150 g and 170 g.
Open points
Water resistance on a copy is not certified. Gaskets and case tube threads vary by batch. A 300 m rating on a copy is a claim, not a test result. Pressure test the watch before use in water. Lume duration and movement accuracy also vary by batch. Ask the seller for the batch date.