The Sensex at the Bombay Stock Exchange gained 123 points, or 0.7 percent, to close at 17,831, on fag-end buying by investors, amid firm European markets, today. The Nifty at the National Stock Exchange rose 44 points, or 0.8 percent, to 5,412.Stock markets in Japan, China, Hong Kong, Singapore and South Korea ended mixed.The rupee depreciated 35 paise, to 49.50 against the dollar. Gold lost 40 rupees, to 28,490 rupees per ten grams in Delhi. Silver dropped 800 rupees, to 56,500 rupees per kilo.And US crude oil futures climbed 50 cents, to 99.21 dollars a barrel, while Brent crude crossed 118 dollars a barrel.