Extending its gains for the third straight session, gold prices on Thursday surged by Rs. 335 to Rs. 32,835 per 10 grams at the bullion market in the national capital, amid a weaker rupee against dollar, according to the All India Sarafa Association.Silver, too, followed gold, gaining Rs. 350 to Rs. 39,700 per kg due to increased demand from industrial units and coin makers.On Tuesday and Wednesday, gold prices gained by Rs. 200 and Rs. 30, respectively.Traders said a weaker rupee against the dollar and safe-haven buying contributed to the surge in the prices of the yellow metal. Besides, a firm trend overseas helped the rise in gold prices, they added.