There are 4 main precious metals https://www.pacificpreciousmetals.com/blog/supply-chains-gold-and-silver-markets: gold, silver, platinum and palladium. These 4 metals are relatively rare and have a known, documented, relatively high economic value that is recognized worldwide. All four metals are used in the production of fine (precious) jewelry. There are those who feel that copper should be added to this list because it is becoming increasingly scarce.