The Aurora Diamante is the most expensive writing instrument till date. Only one is for sale per year. The Aurora Diamante contains over 30 carats of De Beers diamonds on a solid platinum barrel. It has a two-tone, rhodium-treated, 18KT solid gold nib and is personalized with a coat of arms, signature or portrait. Aurora Pens says it is the only over 30 carat pen in the world.