Sapphire glass is an extremely scratch resistant synthetically manufactured glass. It is used to make watch glasses.
Ship’s chronometers are timepieces that, since the 17th century, were taken on board ships to help establish the longitudinal position of the vessel. They are mostly fitted with a chronometer escapement and special mounting.
Skeleton watches have watch casings and various parts with numerous openings to allow a view into the watch’s interior. Skeleton hands are hands with openings into which fluorescent materials can be inserted.
This term refers to a second hand that is not, as is normal in modern watches, fixed at centre of the watch together with the minute and hour hands, but which has a smaller dial of its own elsewhere on the facia. This kind of seconds-display demands a completely different movement construction than a normal watch.
A small spiral shaped spring one end of which is fixed to the balance wheel and the other to the balance spike. Like the balance wheel, the spiral spring is part of the regulating mechanism of the watch.
A non-rusting steel alloy of nickel and chrome. Since stainless steel is easily ground and polished, heavily worn watch housings made of this material can be successfully restored. Even for low cost watches, the once normal brass housings have largely been replaced by stainless steel. In very expensive watches, the stainless steel is sometimes combined with valuable gold alloys (585 and 750 gold) to create bi-colour housings.