For those who think Gold isn't a currency but a commodity look at the price of Gold vs Oil vs Copper after China's devaluation of their currency.
Gold went UP when the other Commodities went down.
Gold is the safest currency in the world.
Not all commodities move up and down equally or at the same time. A currency, by definition, is widely circulated and accepted as a medium of exchange for goods or services. I've never once shopped in a store or ate in a restaurant that accepted gold as currency. I've paid in dollars, pesos, euros, and pounds, but never in ounces of gold.
Gold used to be the standard around which some countries built a currency, but that day has gone. It's a commodity held in reserve as a store of value by some people and countries, but it cannot be easily exchanged into any goods or services, merely bought and sold with currency (as other commodities are).