Oil and diamond supplies are governed by cartels to influence price.
Gold production influenced by price increases or declines, but most gold is not consumed. It sits around for the world to speculate over when everyone freaks out.
Oil is not governed by a cartel.
OPEC is long dead as a factor.
Gold is fairly well controlled. I mean, the price is set in London in what has traditionally been called the “Morning Gold Price Fix.”
And if you want to see “cartel like action”, look at silver.