OMEGA Seamaster 300 234.30.41.21.03.002: specs and what to check

Same depth, different watch

Two OMEGA references documented on this site are rated to three hundred metres, and they are not variants of each other.

• This one — Seamaster 300, calibre 8912, 60 hours, 41 mm
• The Diver 300M — calibre 8800, 55 hours, 42 mm

A listing built from the depth rating and the word Seamaster will get the movement wrong, the reserve wrong and the diameter wrong all at once.

The reserve is the quickest cross-check on paper: sixty hours here, fifty-five there. If a seller has written 55 against an 8912, they have copied a specification from another watch, which tells you how much of the rest of their description to trust.

Forty-eight millimetres, and twenty-one between the lugs

OMEGA publishes both figures, and they answer two different questions.

48.00 mm lug to lug is what determines whether the case fits a wrist. It is seven millimetres longer than the diameter, so anyone judging this watch by "41 mm" is underestimating it.

21 mm between the lugs is what determines what you can put on it. Odd widths are poorly served: strap makers build to even numbers, so a 20 mm band sits loose in the gap and a 22 mm one simply will not enter it.

Tell a buyer both numbers before they ask. Together with the published weight of 156 g, they describe the watch on the wrist far better than the diameter does.

The coating you cannot reach

The crystal is specified as domed, scratch-resistant sapphire with anti-reflective treatment inside.

Read the last word. The treatment is on the inner face only — not on both sides, as it is on several other OMEGA references documented here.

Two consequences. There is nothing on the outside to scratch or wear off, so outer-surface marks are on the sapphire itself. And anything wrong with the coating is behind the glass, where no polish can reach: hazing, bloom or a patchy sheen means a crystal replacement.

Hold the watch so a light rakes across the crystal at a shallow angle and look through it rather than at it. This is the fault most often missed at a viewing and most often reported after delivery, because it is invisible in photographs.

The clasp does micro-adjustment

OMEGA specifies a foldover clasp with comfort setting — a small on-the-fly adjustment built into the clasp itself.

That mechanism is a moving part with detents, and it is used far more often than a clasp's main hinge. Run it out to full extension and back several times. It should move with a definite click at each position and hold where you leave it; a comfort setting that slides freely under load is worn.

Then close the clasp and pull firmly on the bracelet. At 156 grams this is a substantial watch, and the clasp is the only thing between it and the floor.

Case and movement, for the record: steel, 41 mm, 13.85 mm thick, blue dial, calibre 8912, self winding, 60 hours, listed by OMEGA as Master Chronometer certified.