Silver prices tumbled to a three-week low by losing Rs 4,900 to Rs 90,900 per kg, while gold slipped Rs 100 to Rs 78,700 per 10 grams in the national capital on Thursday on frantic selling by stockists and retailers, according to the All India Sarafa Association. The yellow metal of 99.5 per cent purity declined Rs 400 to Rs 78,300 per 10 grams on Thursday. Price of gold of 99.9 per cent and 99.5 per cent purity closed higher at Rs 78,800 and Rs 78,700 per 10 grams, respectively, on Wednesday. Silver also dropped Rs 4,900 to trade at Rs 90,900 per kg, marking a steepest fall on poor offtake by jewellers and coin makers. Earlier, the white metal had slumped Rs 4,600 on November 4. On Wednesday, silver saw its steepest single-day jump of Rs 5,200 and regained the Rs 95,000 per kg level after a gap of two-weeks in the national capital. Traders said the sentiment was downbeat largely in sync with a firm trend overseas amid uncertainty over the implications of US President-elect Donald