The Poinçon de Genève certifies, in its own words, "all the qualities of craftsmanship to ensure regular and long-lasting operation," covering the craftsmanship, the regularity and durability of operation, and certificates of origin.
It rests on Geneva cantonal law I 1.25, passed by the Grand Council of Geneva in 1886 and updated in December 2008 as the law relating to the Geneva Laboratory of Horology and Microengineering.
Two bodies, not one. The State of Geneva is the legal guarantor; it delegates control and marking to TIMELAB, the Geneva Laboratory of Horology and Microengineering, which operates the Poinçon de Genève Office. Sources routinely collapse the two: the guarantee is the State's, the certification work is TIMELAB's.
It is a craftsmanship and origin mark, not a rate certification. TIMELAB separately runs the Observatoire Chronométrique+ for chronometer testing.