Here is part of the enactment of 1300 under Edward I; I've edited it because it is a bit lengthy:
It is ordained that no goldsmith of England...shall henceforth make or cause to be made anything of gold or silver, except it be of true alloy...and that the wardens of the craft shall go from shop to shop among the goldsmiths to essay if their gold/silver be of the same touch that is spoken of before.
This job of course became impossible as the number of goldsmiths increased, and so guilds formed composed of wardens who carried out the assaying from assay halls which is where
hallmark comes from.
Of course this is a hugely shortened account of hallmarking in Britain, a subject to which whole books are dedicated.
Jackson's Silver and Gold Marks offers a good history in its introduction.
Miles