One of many articles about how it's done: Gold and Silver Price Manipulation from the Top Down
Hammering the price of gold hard, while artificially pumping up the stock market. Not a good, or viable, long term solution. Excellent buying opportunity, though.
The price of gold in U.S. dollars is not really the price of gold itself. Rather, it is the value of the U.S. dollar priced in gold. A rising gold price is another way of recording the falling value of the U.S. dollar. Ultimately, even poor measures of inflation like the CPI will reflect changes in the price level, but the very sensitive price of gold detects this minute by minute.