Falling for the third straight day, gold declined Rs. 50, to Rs. 30,750 per ten grams at Delhi's bullion market on Friday, on sustained selling by stockists, following sluggish demand, and a weak global trend.Silver tumbled Rs. 2,000, to Rs. 50,300 per kilo. Silver coins plunged Rs. 1,000, to Rs. 85,000 for buying 100 pieces.Overseas, gold fell one percent, to 1,308 dollars an ounce, on speculation that the US Federal Reserve will soon taper bond purchases. Goldman Sachs Group predicted further declines.