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.