Rising for the sixth straight session, gold gained 150 rupees, to 30,310 rupees per ten grams at Delhi's bullion market, today, on sustained buying ahead of the festive and marriage season, amid a firm global trend. Silver added 400 rupees, to 53,050 rupees per kuilo, on increased offtake by industrial units and coin makers.Overseas, gold shot up 24 dollars, to 1,605 dollars an ounce. Silver jumped 1.4 per cent, to 27.34 dollars an ounce.