Gems and gold as jewekry have been indivisible since at least the third millenium BC. All civilizations that have known gold have prized it for its beauty as well as its rarity. And because it is a soft metal, which allowed it to be easily worked, it was easy to use it for jewelry.
The earliest gold was found by panning river beds for it, but by Roman times, open-cast and tunnel mining were used in Europe. And then the New World was discovered, and the Spaniarfs brought great quantities of gold from the conquered nations.
Subsequent gold discoveries
California – 1848
Australia 1851
South Africa – 1880s
Until 1975, the purity of gold was measured in karats, with 24 karat being the purest (and the most seldem used, because of its softness).
After 1975, the term used became “Fineness”.
In Europe, for example, pure gold is stamped 1000 fine. 18K is 75 percent or 750 fine. So, an 18K ring made in Europe would be stamped 750.