Gold prices slipped 230 , to 20,400 rupees per ten grams at Delhi's bullion market, today, on heavy selling by stockists, triggered by negative global cues. Silver posted a sharp fall of 1,540 , to 42,850 rupees per kilo. In New York, gold had dropped 25 dollars, to 1,346 dollars an ounce, yesterday. Silver lost 4.5 per cent, to 27.47 dollars an ounce