Is it correct that 9ct gold is harder wearing than 18ct gold?
It is a popular myth that 9ct is harder than 18ct gold but after much scientific research this has been dispelled. Pure gold is 24 carat and 9ct must be at least 9 parts gold in 24, equivalent to 37.5% gold and the other 62.5% other metals such as copper, silver, palladium or zinc. 18ct must be at least 18 parts gold in 24, 75% gold and 25% other metals. These ‘recipes’ can be altered to affect the hardness of 9ct and 18ct gold. Generally 18ct gold alloys are both harder and more durable than their 9ct equivalent. 9ct gold alloys are often more brittle than 18ct alloys which tend to be more resilient. 18ct gold reacts better to the mechanical processes that the alloy is subjected to such as rolling, stretching, bending, hammering, etc. These processes tend to make 9ct alloys more brittle.
