2013 United Kingdom Great Britain 1/20 oz Proof 24 Karat Gold Britannia PF70 NGC First Year of Issue! Beginning in 2013, the Britannia began featuring a new design by a different British artist each year new purer precious metals standard (.9999) new denominations  including this Britannia Gold Proof 1/20 oz. coin 2013 was the first year of issue for the 1/20 oz. This spectacular coin is one of a limited number in this mintage to receive a PF70 grade from the NGC.