Tissot Seastar 1000 40mm T1208071105100: specs and what to check

Mineral, not ceramic

Tissot is specific about the bezel and it is the detail most likely to be misgraded.

The published specification is 316L stainless steel with mineral bezel ring, listed under case options as a mineral bezel ring.

That is a third material, distinct from the two people expect on a modern diver. Aluminium dulls and fades. Ceramic is close to scratch-proof and chips instead. Mineral glass scratches — in ordinary use, from ordinary contact — and the marks are fine, bright and visible under a raking light.

Two practical consequences.

Do not over-discount visible surface marking. On a mineral ring it is expected wear on a wear surface, not evidence of abuse.

Do not write "ceramic bezel" in the listing. Buyers cross-shopping divers know the difference and price it. Write what Tissot writes.

Look for chips and cracks in the ring as well, since mineral glass will fracture under a hard enough knock, and check whether the ring is seated evenly all the way round.

Anti-clockwise, and it must mean it

The bezel is described as anti-clockwise rotating — the dive-watch convention, where the bezel can only ever move in the direction that makes elapsed time read longer.

Test it as a safety component. Grip it and try clockwise: nothing should happen, at all. Then run it anti-clockwise through a full turn, feeling for clicks that are soft, missing or gritty.

Then check the Super-LumiNova. Tissot lists luminous material on the hands and on the case, which on a diver means the bezel marker. Kill the lights and compare: the pip and the hands should be the same colour and should fade together. Under a torch, a ring swapped during an earlier repair announces itself at once, while daylight hides it completely.

Thirty bar, stated conditionally

Read the rating exactly as Tissot writes it: water-resistant up to a pressure of 30 bar (300 m / 1000 ft) with screw-down crown.

The qualification is part of the specification. The rating exists with the crown screwed down — not with it pulled out, and not with it merely pushed to.

Tissot also lists screw-down crown and caseback among the case options, so there are two threaded seals here rather than one.

Work the crown: unscrew and rescrew it several times, feeling for the thread catching cleanly on the first quarter turn. Grit, hunting for the thread or a crown that will not sit flush all point at damage to the tube.

One more time, because it applies to every diver here: a depth figure is a factory specification, not a measurement of the example on your bench. Test it, or say plainly that nobody has.

Clasp, size and movement

The clasp is a folding clasp with safety lock and push-buttons. Open the safety lock, close it, and confirm it re-engages with a definite catch. It is carrying 148.00 g of steel every time the watch is put on.

Published dimensions: 40.00 mm in both directions, 12.48 mm thick, 20 mm lug width, bracelet reference T605049459, listed as interchangeable quick release — so unlike the PRX references here, an ordinary 20 mm strap will fit this watch.

The movement is given as Swiss automatic, 80 hours, with a patented Nivachron balance spring and a date. No calibre name, jewel count or accuracy figure is published, so do not supply one.

The caseback is both screw-down and see-through, which is a useful combination: you get a sealed case and a window onto the movement.