Sapphire crystal is the favoured material for watch crystal due to its exceptional hardness (9 on the Mohs scale). Using sapphire crystal is far more expensive to produce than mineral or acrylic crystals. Domed crystals are also far more expensive and difficult to produce than flat crystals.
A system used to protect the very fragile pivots of the balance staff against breakage. The jewels for the pivots of the balance staff are elastically fitted to the main plate. In response to a severe shock, they give first. A watch with shock absorption properties should be able to meet the demands of DIN 8308-A. The testing includes the watch being hit by a hammer at 4.4m/s (equivalent of the watch being dropped from a one metre height onto a solid wooden floor). The watch must then not show a rate of deviation of more than +/- 60 seconds a day.
An alloy of steel, nickel and chrome. Although difficult to work with, it is resistant to rust, extremely tough and anti-magnetic.
A luminous paint used on the dials of watches that does not display any radioactive properties. The luminous effect is based on the principle of phosphorescence. Super‑LumiNova® therefore needs to be charged by an external light source. As many as 15 to 20 coats of Super‑LumiNova® paint are applied to quality dials in very small measures to ensure that luminous dials are effective whilst not encroaching on the aesthetic qualities of a quality dial.