Correlation among Gold, Money and Interest; and Forward Sale of Gold

Today gold coin and silver coin or trade bill of Exchange which is equivalent to previous two are taken out of circulation and banknote (paper money) has come into circulation, instead. However gold coin and gold bullion that are issued by state or special agencies have been still used as saving tools. In addition, central banks are stocking gold as a reserve in order to support their national currencies and to make foreign payment. That is why; these items have still the feature of being money and the rules of exchange (sarf in fiqh) are operative on its purchase and sale. On the other hand the gold items other than coin and bullion lost their qualification of being money. For this reason purchase and sale of such items with banknote is not sarf and it is not inconvenient to buy and sell them with terminal payments.