OK, then insert TROY before oz. All said, I was raised by my grandparents who survived a depression. You should hear the tirades my grandfather goes upon about the lack of a gold standard. When currency (paper) goes to pot (which is weighed in regular ounces iirc) gold and gems retain value.
Look at De beers. They created a demand for gold (remember the annual commercials with the Vivaldi score in the background) Then they witheld (or bottlenecked anyhow) the supply. Diamonds became "forever" and instantly valuable.