How does the gas escape valve operate on a rolex sea-dweller watch?

as the helium and hydrogen gas has the smallest atomic build among every thing in universe, they can escape from even solid metallic cups... deep sea divers if they are diving in deep sea for a long time, they must go under various decompression modes which some times take more than a day... during these decompression modes they have to breath oxygen mixed with helium or hydrogen to prevent nitrogen bubling in their blood causing death or paralysis instead of normal air mixture like oxygen and nitrogen as these decompression gasses can escape everything to known universe they can go in to the even best sealed diving watches... after the decompression period it was a well known issue that these diving watches were blowing their Christals up causing injuries or at least damaging the surroundings and these prestigious watches due to helium or hydrogen build up in them... to prevent that, some deep sea watches have a one way valve letting the excessive presure out as a solution to this problem which is called ''gas escape valve''