FDC = Fleur de Coin Club silver medallion, issued by the British Royal Mint to any of its direct customers who spend enough money with them. We think FDC may stand for something far less complimentary in view of the facts that (1) we sell most RM new products at lower prices, (2) secondary market prices are often much lower. I suppose we really should not be having these cynical thoughts, should we? Diameter 50mms, alloy .925 silver.