Precious Metals
The Difference Between Carats is Surprising
Gold alloys are always calculated by weight. For example 18 carat gold must contain at least 18 parts gold out of 24 parts total (75%). The proportions by volume can show a startling difference.
The graphic below shows the proportions by volume of gold, silver, copper and zinc in typical 18 carat and 9 carat yellow gold alloys.
9 Carat Only Contains 37.5% Gold!
As you can see, 9 carat yellow gold contains only 37.5% gold by volume. Consumers who saw gold alloys being mixed would only want to buy 18 or higher alloys. Indeed the more you know about all the qualities of gold alloys, the more you would only accept 18 carat or better.