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Top-tier supplier movement · caliber ETA Powermatic 80 (Tissot): Swiss automatic, 21,600bph, 80h PR, 21j; Tissot-branded ETA Powermatic 80; used in PRX, Le Locle, and Seastar 1000 · 80h power reserve (3.3 days)

Also uses ETA Powermatic 80 (Tissot)

Tissot PRX Powermatic 80 Ref. T137.407.11.041.00, blue dial, steel case
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Tissot PRX 35 Powermatic 80 Ref. T137.207.11.031.00, silver dial, steel case
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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.
AreaWhat to checkWhat is correctRed flag
caseHelium escape valve thread integrityValve unscrews and threads back in fully with clean engagement; seals flush with the case when tightenedValve that will not thread back fully or feels loose when tightened; water resistance is compromised
caseCeramic bezel insert conditionUnidirectional ceramic insert fully intact with no chips; pip lume bright and undamagedAny chip at the pip or at the 12 o'clock position; ceramic cannot be repaired
crownScrew-down crownCrown threads down fully and securely for 300m water resistance; no cross-threading or strippingCrown 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.

Known reproduction risks

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LOW

The Seastar 1000 is not heavily replicated. The ceramic bezel insert is a useful authenticity tell: low-cost replicas typically use aluminum.

  • Aluminum bezel insert instead of ceramic
  • Missing "SEASTAR" embossed caseback emblem
  • Crown that pushes rather than screws

Dial variants by era

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EraDescriptionIdentifiers
2018 to presentBlue, black, or green dial with applied luminous hour markers. Unidirectional rotating bezel with ceramic insert. "SEASTAR 1000" at 12 above center. "POWERMATIC 80" at 6.
  • Ceramic bezel insert with printed minute track and 60-minute scale
  • Luminous applied markers, not painted-on
  • "SEASTAR 1000" text at 12
  • "300M / 1000FT" water resistance marking below center
  • "SWISS MADE" below 6

Service part flags

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Bezel insert

Original: Ceramic insert in matte black (or matching dial color). The insert is secured in the bezel with a click mechanism; it rotates counterclockwise freely and locks clockwise.

Replacement tells
  • Aluminum insert on a watch claimed to be the ceramic-bezel Powermatic 80 version
  • Insert that rotates in both directions is loose or incorrectly fitted
  • Matte surface replaced by a glossy insert
Crown

Original: Screw-in crown with Tissot logo. The crown must be screwed down completely to maintain the 300m water resistance. Unscrewed crown in the winding position is normal for setting.

Replacement tells
  • A push-pull crown on the Seastar 1000 is not correct for this reference

Case back markings

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2018 to present
  • Solid caseback with embossed Seastar emblem (sea creature design)
  • "SEASTAR" arched at top
  • "300M / 1000FT" printed on caseback
  • "WATERRESISTANT" marking
  • Reference T120.407 prefix
  • Serial and "SWISS MADE"

Movement tells

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  • Same ETA C07.611 Powermatic 80 as the PRX and Le Locle. Beat rate and 80-hour power reserve checks are the same.
  • After any service, the screw-in crown and caseback gasket must be replaced if the watch is to be used in water.
Sources: Tissot Seastar 1000 official page.

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