Gold rose to a one-month high in New York and London as a weaker dollar increased demand for the precious metal as an alternative investment. Platinum climbed to the highest price in 17 months. The U.S. Dollar Index, a six-currency gauge of the strength of the greenback, slid as much as 0.9 percent. (BTW, the US Dollar Index is calculated by factoring in the exchange rates of six major world currencies: the euro, Japanese yen, Canadian dollar, British pound, Swedish krona and Swiss franc. This index started in 1973 with a base of 100 and is relative to this base. This means that a value of 120 would suggest that the U.S. dollar experienced a 20% increase in value over the time period.) More from Bloomberg