St. Germain

St. Germain is a legendary figure, said to have appeared at various points in history throughout medieval Europe's high society and claimed to be among other things, an immortal, a time traveler, and a technician capable of repairing broken jewels. Most of the legends associated with St. Germain are rather dubious ones, and as such much of it is considered by many to be false.

(Source: Toaru Majutsu no Index Wiki)