Antique and Vintage Jewellery Lecture:

Around 1800 Napoleon disbanded the guilds and left the regulations of gold and silverware to lawmakers.

The guilds were responsible for ensuring the integrity of relevant trades. They designated assay-masters to inspect items made from precious metals verifying the correct alloy was used. Their methods were quite effective; in fact, most of their regulations were later incorporated into legislative laws. Therefore, we are still operating under similar principles today.

What requirements must an object made from a precious metal meet?

This varies depending on the country of manufacture, its intended market, or its current location. To put it succinctly: it must bear a (hall-)mark. However, the presence of a mark doesn't always guarantee the object is as described. For instance, a gold mark on a piece of iron claiming it to be gold would not convince many, but a gold mark on a piece of brass might be more challenging to dispute for most. This indicates that a mere mark is insufficient. Hallmarks must adhere to specific standards, which differ from country to country and across different periods.