Gasket

No definition of the word was found in any standard, museum record or law opened for this entry. The clearest functional account comes instead from a manufacturer writing about its own watches. Omega states: "The water resistance of a watch is ensured by gaskets placed between the crown, the pushers, the crystal, and the watch case." That is the whole mechanism. A case is not watertight in itself; its joints are sealed, and the gaskets are what seal them.

Omega is equally explicit, again about its own product, that the seal is a consumable: "These gaskets deteriorate over time under the influence of external factors such as temperature variations, pollution or chemicals and must be regularly replaced to guarantee the water resistance of the watch." Its description of a complete service says that "all gaskets ensuring the water resistance are replaced". These are the brand's statements about its own watches, not an independent requirement on anyone else's.

The Swiss industry norms the gasket's seat rather than the gasket's meaning. The Federation of the Swiss Watch Industry's list of available NIHS standards includes NIHSG 62-02, Joints toriques – Logements (O-ring gaskets, housings; 1968, revised 2022), NIHSG 62-04, Joints plats – Logements (flat gaskets, housings), and NIHS 61-12, Mineral and sapphire watch-glasses – Part 2: Assembly to the case by adhesive or using a gasket (2003). Testing the result is a separate matter, governed by ISO 22810:2010, Horology — Water-resistant watches, which "establishes the requirements and specifies the test methods used to verify the water resistance of watches".