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. This value is in metric tons, and is 1457.2 t.

It has been estimated that all the gold mined by the end of 2011 totaled 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.

This constant calculates the total value of gold for the top 40 countries based on reported gold reserves, which is currently 1457.2 t.

References

The definition of Gold Reserves is from Wikipedia (https://en.wikipedia.org/wiki/Gold_reserve).