"T Swiss Made T" or "Swiss T 25" : what does it mean ?
Some indexes and hands coated with a luminescent material on the dial in order to read the time in the dark environment.
The use of radioactive material is strictly defined by ISO 3157 Standard which allows only two types of radionucleides : tritium (3H) and promethium (147 Pm). It is important to specify that these radionucleides emit a radiation of low energy, does not affect our health.
Deposits activated by tritium : T
Deposits activated by promethium : Pm
On the other hand, timepieces with a higher value, such as divers' watch, must be marked as follows : T＜25
Deposits activated by tritium : T 25
Deposits activated by promethium : Pm 0.5
The indication "T Swiss made T" means that the watch manufactured in Swiss and contains a certain quantity of tritium that emits less than 227 MBq (7,5 mCi).The indication "Swiss T25" means that the watch is Swiss and contains a certain quantity of tritium that emits less than 925 MBq (25 mCi).
