Strengthening gains for the second straight session, gold prices today edged up by Rs 10 to Rs 31,580 per 10 grams at the bullion market on persistent buying by local jewellers amid a firm trend overseas. Silver prices too surged by Rs 690 to Rs 40,600 per kg backed by increased offtake by industrial units and coin makers. Traders said continued buying by local jewellers at the domestic spot market and a better trend overseas mainly kept gold prices higher. Globally, gold rose by 0.34 per cent to USD 1,256.50 an ounce and silver by 0.37 per cent to USD 16.06 an ounce in New York in yesterday's trade. In the national capital, gold of 99.9 per cent and 99.5 per cent purity moved up by Rs 10 each to Rs 31,580 and Rs 31,430 per 10 grams, respectively, The precious metal had gained Rs 210 yesterday. Sovereign, however, remained unaltered at Rs 24,800 per piece of eight grams in limited deals. In line with gold, silver ready jumped up by Rs 690 to Rs 40,600 per kg, while weekly-based delivery shed Rs 60 to Rs 39,200 per kg. Silver coins, however, remained steady at Rs 75,000 for buying and Rs 76,000 for selling of 100 pieces.