Glossary of watchmaking
Glossary of watchmaking
Swiss T 25 (T Swiss made) So that watches (and timekeeping devices in trendy) Swiss made dive watch    can be read within the dark, the numerals, hour markers and arms need to be covered with a luminescent substance. As a fashionable rule, the light emitted is either photoluminescent (the usage of power absorbed from a light source) or radioluminescent (the usage of the radioactive belongings of the coating substance). Radioluminescence is commonly reserved for watches supposed for expert use, such as military watches or diving watches, and is strictly regulated by way of ISO 3157 which allows only styles of radionuclides: tritium (3H) and promethium (147 Pm). Both those radionuclides emit very low-power radiation. ISO 3157 gives for elective marking of timekeeping gadgets that emit less than a certain fee. This marking may be shown on the dial as follows: tritium-activated deposits: T promethium-activated deposits: Pm In contrast, devices that emit above this price have to be marked as follows: tritium-activated deposits: T 25 promethium-activated deposits: Pm 0.5 "T Swiss made T" method that the watch is Swiss and contains a positive amount of tritium that emits much less than 227 MBq (7.5 mCi). "Swiss T<25" method that the watch is Swiss and contains a sure quantity of tritium that emits less than 925 MBq (25 mCi). Most Swiss watches use photoluminescent light emission, from time to time indicated by means of the elective marking, "L Swiss Made L". Terms with the equal letter Safety roller Sapphire Scale Scratchproof Screw Second Secret spring Secular Perpetual calendar Self-winding (Automatic) Set (to) Setting Ship's chronometer Shock absorber Shockproof Sidereal day Silent Simple calendar (watch) Skeleton Skeleton movement Slide Smoky quartz Snailing Snap Snow placing Sodalite Solstice Souscription (watch) Specific gravity Spectroscope Spinel Split-seconds (chronograph) Split-seconds chronograph Spring Stamping Stamping press Steel Step motor Stippling (Spotting) Stone Stopwork Strap Striking mechanism Stud Subsidiary seconds Sunray brushing Sunrise and sundown Sweep seconds Swiss T 25 (T Swiss made) Sympathique Synthetic ruby (Scientific ruby) Synthetic stone

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