The gold carats commonly used in engagement and wedding rings are 9ct, 14ct and 18ct. The greater amount of pure gold used to manufacture the metal, the more valuable and expensive the metal will become. The remainder of the metals are made up of a combination of alloys and different metals which can help to give the metal its unique appearance, such as a different colour. Disclaimer : The chart is for illustration purposes only. We do not work with palladium or platinum.