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Top-tier supplier movement
Also uses ETA Powermatic 80 (Tissot)
Large case: suits wrists 7 in+ (18 cm+)
43 mm case. A bold, statement-size wear. Best suited to larger wrists where the case sits flush.
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Authentication
Test the helium escape valve at 10; a valve that will not thread back fully needs replacement before any dive use.
Known issues in the market
- The helium escape valve at 10 o'clock must thread in and out cleanly; a valve that will not reseal fully compromises 300m water resistance.
- The ceramic bezel insert is the most damage-prone component; inspect for chips at the pip.
| Area | What to check | What is correct | Red flag |
|---|---|---|---|
| case | Helium escape valve thread integrity | Valve unscrews and threads back in fully with clean engagement; seals flush with the case when tightened | Valve that will not thread back fully or feels loose when tightened; water resistance is compromised |
| case | Ceramic bezel insert condition | Unidirectional ceramic insert fully intact with no chips; pip lume bright and undamaged | Any chip at the pip or at the 12 o'clock position; ceramic cannot be repaired |
| crown | Screw-down crown | Crown threads down fully and securely for 300m water resistance; no cross-threading or stripping | Crown that does not thread down fully or feels loose when tightened |
Common legitimate replacements
- Helium escape valve gaskets are a service part; replacement is inexpensive and should accompany any full service.
- Powermatic 80 service interval is nominally 8 years; factor this into pricing on used Seastar examples.
Expert resources: Tissot Seastar documentation at tissotwatches.com. WatchUSeek Tissot subforum for helium escape valve service notes and Seastar ceramic bezel assessment.
Authentication guide
Last reviewed June 2026
The Seastar 1000 Powermatic 80 is Tissot's dive watch with a 300m water resistance rating and a ceramic bezel insert. The caseback carries a Seastar emblem. Inspection focuses on the ceramic bezel insert integrity and the screw-in crown gasket.
Sources: Tissot Seastar 1000 official page.






