A system is what it does, and gold is popular for jewelry because it’s a useful way to wear money.

Off topic and this might be apocryphal, but I heard on the internet a good reason to keep “money” in the form of gold chains and other jewelry, is that it counts as personal property, so if you’re arrested during a drug bust or trafficking women, your cash and bank accounts may be seized, but whatever you wear to prison gets put in a ziplock bag and returned to you when you leave :)