Gold foam

Scientists have discovered a method to create 18-carat gold using a mixture of protein fibers and a polymer latex instead of a conventional recipe of gold and base metals, according to research published.

The substance, a type of gold foam, has the same toughness, strength and heat resistance as regular 18-karat gold, but is much lighter due to the use of plastics instead of metal. The gold also contains tiny air pockets, which are invisible to the naked eye. The scientists said the substance could be used in watches, jewelry, radiation shielding, catalysis, and electronics.

https://www.kitco.com/news/2020-01-22/Look-ma-18-carat-gold-jewelry-made-with-plastic-not-metal.html