This 1/20 oz Gold Britannia from 2013 is from the. Year of 0.9999 gold fineness and 1/20 oz gold weight in the Britannia series, and is the. Year with this design on a 1/20 oz Gold Britannia. This coin comes in a beautiful proof finish and has been graded a near perfect PF-69 by NGC, a top coin grading service.