Tissot Seastar 1000 Chrono T1204171104103: specs and checks

Three things are locked before you start

Tissot states the rating as 30 bar (300 m / 1000 ft) with screw-down crown and push-buttons, and lists screw-down crown and caseback among the case options.

That means the chronograph pushers are threaded. They screw down against the case and they do not operate at all until you unscrew them.

A dealer who does not know that presses a pusher, gets no response, and writes off the chronograph. Worse, a dealer who presses harder can damage the pusher tube.

So the sequence at inspection is: unscrew the crown, unscrew both pushers, then test. And the sequence at handover is to show the buyer the same thing, because a customer who cannot start their new chronograph will call you before they work it out.

Screwing them back down afterwards is what the rating depends on. Confirm both thread cleanly and seat flush.

ADD and SPLIT are separate tests

Tissot lists the movement's functions in detail: EOL battery end-of-life indicator, 30-minute and 1/10 second counters, a central 60-second chronograph hand, and ADD and SPLIT functions.

Most inspections test start, stop and reset and stop there. That exercises neither of the named functions.

ADD accumulates timing across several start-stop cycles without resetting. Start it, stop it, start it again, and confirm the elapsed count continues from where it was rather than restarting.

SPLIT freezes the display while timing continues underneath. Start it, engage the split, watch the hand stop, then release — the hand must jump forward to catch up with the true elapsed time. A split hand that simply resumes from where it was frozen has failed, and a start-stop test would never have shown it.

Also check the EOL indicator: a seconds hand moving in multi-second jumps is the movement reporting a flat battery, not a broken watch.

Aluminium wears differently again

The bezel here is stainless steel with an aluminium bezel ring.

That is the third bezel material across the Tissot references documented on this site — the Seastar 40 uses mineral, the PRX has a plain steel bezel — and each grades differently.

Aluminium does not chip like ceramic or scratch bright like mineral glass. It fades, particularly on coloured inserts, and it dents, taking small permanent marks where it has been knocked. A twenty-year-old aluminium insert that has gone pale is doing exactly what aluminium does.

So describe the material and let the buyer price the patina. And check the ring is seated evenly, with the Super-LumiNova marker matching the hands under a torch.

The bezel is anti-clockwise rotating: try clockwise first, and nothing should move.

The extension nobody opens

The clasp is a folding clasp with safety lock, diver extension and double push-buttons.

The diver extension is a hinged panel that lets the bracelet open out over a wetsuit sleeve. On a watch that has never been diven — which is most of them — it has been folded shut since the day it was sold.

Open it all the way. Check the hinge is not sprung, that it lies properly flat when closed, and that its own catch holds. Then work the double push-buttons and the safety lock: at 180.00 g this is the heaviest Tissot documented here, and the clasp is all that is holding it.

Size and crystal

45.50 mm in both directions, 12.82 mm thick, 22 mm lug width, bracelet T605046894, interchangeable quick release.

Forty-five and a half millimetres is large by any current standard. Say so plainly rather than letting a photograph decide.

The crystal is sapphire with double antireflective coating on top and bottom sides — unusual among the Tissot references here, which mostly coat the inner face only. A top coating can be scratched and worn, so inspect the outer surface as well as looking for interior haze.

Made in Switzerland, two-year warranty from new.