A gold reserve is the gold held by a national central bank, intended as a store of value and as a guarantee to redeem promises to pay depositors, note holders (e.g. paper money), or trading peers, or to secure a currency.
It has been estimated that all the gold mined by the end of 2011 totalled 171,300 tonnes. At a price of US$1,500 per troy ounce, reached on 12 April 2013, one tonne of gold has a value of approximately US$48.2 million. The total value of all gold ever mined would exceed US$8.2 trillion at that valuation.
However, there are varying estimates of the total amount of gold mined to date, mainly because gold has been mined for thousands of years around the world. Another reason is that some countries are not particularly open about how much gold they are mining. In addition, it is difficult to account for gold output in illegal mining activities.
Gold Reserves - Wartime Relevance (Example from World War II)
During most of history, a nation's gold reserves were considered its key financial asset and a major prize of war. A typical view was expressed in a secret memorandum by the British Chief of the Imperial General Staff from October 1939, at the beginning of World War II. The British Military and the British Secret Service laid out “measures to be taken in the event of an invasion of Holland and Belgium by Germany” and presented them to the War Cabinet: