Dr Peter Wothers weighs a volunteer from the 2012 Christmas Lectures audience with 24 carat pure gold. Finding himself a little short of the right amount, he calls in help from famous chemist Sir Harry Kroto and his gold Nobel Prize medal (awarded in 1996 for his discovery of a new form of Carbon, C60). Calculate your weight in gold: Current gold prices: http://www.wolframalpha.com/input/?i=gold+price Weight in gold calculator: http://www.onlygold.com/tutorialpages/yourweightingold.asp The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Our editorial policy: http://www.rigb.org/home/editorial-policy Subscribe for the latest science videos: http://bit.ly/RiNewsletter