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Cyma chronograph clamshell

Cyma chronograph clamshell


Brand: Cyma
Typology: Vintage chronograph
Year: 1940

Known as the first waterproof chronograph wristwatch, the distinct "Clamshell" case was patented in 1936 by Schmitz Freres & Co. It's a unique two-part compression case with a specialized flared crystal. The

"Clamshell" case is also easily recognizable by the presence of four screws on the reverse side of the case, located under each lug.

The whole design was aimed at increasing the water resistance of the case.

So many manufacturers took advantage of this patent, including Cyma.

This oversize chronograph best represents the mechanical and stylistic ingenuity of the 1940s/50s.

The condition, diameter, and timeless look make it a desirable piece for any collector

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  • General info

    • Reference: Clamshell
    • Serial number: n.a.
    • Case material: Steel
    • Glass: Plexiglass
    • Caseback: Fixed with screws
    • Case diameter: 38.0 mm
    • Bezel Materials: Steel
    • Dial color: White
    • Dial numerals: Arabic
    • General conditions: Great conditions
    • Water resistance rate: Not waterproof
  • Band or Strap

    • Band material: Leather
    • Lug width: 20 mm
    • Buckle type: Classic
    • Buckle material: Steel
  • Movement

    • Calibre: Valjoux 22
    • Movement type: Manual wind
    • Complications: Chronograph