Gold rose 225 rupees, to 28,540 rupees per ten grams at Delhi's bullion market, today, on marriage season demand, and a firm overseas trend. Silver rose 200 rupees, to 56,700 rupees per kilo, on pick-up in demand from industrial units and coin-makers. Silver coins shot up 3,000 rupees, to 65,000 rupees for buying 100 pieces. In London, gold rallied 18.70 dollars, or 1.1 percent, to a six-week high of 1,773 dollars an ounce, as concerns about Europe's debt crisis spurred demand for the precious metal. But silver fell 0.3 per cent, to 34.05 dollars an ounce