Horology glossaryDefined term / helium-escape-valve
Helium Escape Valve
A one-way valve on some dive watch cases that releases helium absorbed during saturation diving, preventing the crystal from popping off during decompression.
Authentication note
Why this detail matters.
A helium escape valve is a functional feature tied to specific dive watch references, not a decoration, so its presence or absence should match what the reference is actually supposed to have. A valve that doesn't operate, or one added to a reference that never carried one, is inconsistent with a genuine watch.