Mumbai, June 13 -- A quick sprint on Friday helped Indian markets close a volatile week with solid gains, as signs of peace in West Asia rekindled investor optimism worldwide. As crude oil slipped below $90 a barrel, buyers who stayed away during a turbulent week trooped in, helping the Street clock the best gains in eight weeks. The Sensex rose 1.7% over the week, while the Nifty gained 1.1%. Most of the gains came on Friday, when the Nifty jumped 2% to close at 23,622.90 and the Sensex 2.3% to 75,527.94, the highest close for both since 8 April. On that day, Indian equities had rallied nearly 4%, cheered by a US-Iran ceasefire announcement. Volatility cooled sharply: the India VIX, which measures expected market volatility, declined from ...