9ct or 18ct: what the numbers on your gold mean

Pure gold is too soft to wear every day, so jewellers mix it with other metals, mostly silver and copper. The carat number tells you how much of the mix is gold, counted in 24 parts. 9ct is nine parts gold out of 24. That is 37.5%, and it is why a 9ct piece is stamped 375.

9ct is the gold most Australians wear. It is hard-wearing and costs less, because most of it is not gold.

18ct is 75% gold and stamped 750. At the same weight it holds exactly twice the gold of 9ct, so it costs more and the yellow is warmer. It is also softer. An 18ct ring worn every day will show scratches sooner than a 9ct one, and a polish brings it back.

You will also see 10ct (417) and 14ct (585) on some of our pieces. Those are the usual standards in the United States, and a few of our imported diamond pendants use them. We label them exactly as stamped.

The same numbers apply to white and rose gold. Rose gold gets its colour from copper. White gold is usually plated with rhodium for a brighter white, and that plating wears thin over the years. We can replate it in the workshop.

If you are unsure about an older piece, our valuer can test it.