A much simpler approach is to alloy gold with titanium. The resulting alloy is stronger and less dense than pure gold. Carat weight is determined on a weight

A much simpler approach is to alloy gold with titanium. The resulting alloy is stronger and less dense than pure gold. Carat weight is determined on a weight fraction and because titanium is low density, a relatively large volume of titanium can be alloyed with a small volume of gold and still have a high carat number. One particular gold-titanium alloy is significantly harder than most steel. https://phys.org/news/2016-07-lab-titanium-gold-alloy-harder-steels.html https://phys.org/news/2016-07-lab-titanium-gold-alloy-harder...