This is the same as the original series 3 1 BTC 2013 coin, but with a solid gold plating applied to the ‘B’ and the outer rim on both sides. This plating is of a higher quality than that of the series 2 10 BTC 2012 ‘Gold B’ coins.
These coins are derived from the series 3 1 BTC 2013 coin of which 2,000* were originally made. 700 of them were converted to this ‘Gold Rim’ version by Casascius.
*20 of these 2,000 coins have been opened; it is not known what the distribution between normal and ‘Gold Rim’ is.