India-focused energy group Essar Energy was the best performing stock on the FTSE 250 on Monday after Citigroup upgraded its rating to 'buy', saying it was well placed to benefit from changes to the energy industry in India."After years of constraints, India now looks to be picking up the pace of energy market reforms in an effort to encourage investment and reduce energy shortages that have plagued parts of the country [...] We see Essar Energy as a key beneficiary of these reforms, allowing much better visibility over what remains a high-potential growth portfolio," said analyst Mukhtar Garadaghi.SOCO International's shares advanced after saying it encountered about 117 metres of net pay section in the H5 fault block of the Te Giac Trang oil field, offshore in the South China Sea.LED technology company Dialight was also a high riser after its first-half results came in above analysts' estimates owing to the strong performance of the Lighting division. Bumi plc fell sharply after returning to trading today, three months after the Indonesian coal producer requested it be suspended on the London Stock Exchange.Gold mining peers Polymetal and African Barrick Gold were among the best performers as the price of the yellow metal rose strongly; gold for December delivery was up 2.3% at $1,324 an ounce in afternoon trade.FTSE 250 - RisersEssar Energy (ESSR) 142.10p +4.72%Soco International (SIA) 375.30p +4.57%Dialight (DIA) 1,124.00p +4.56%Polymetal International (POLY) 623.50p +4.44%Chemring Group (CHG) 310.20p +4.02%Barr (A.G.) (BAG) 565.00p +3.48%Workspace Group (WKP) 450.40p +2.76%Marston's (MARS) 158.00p +2.73%African Barrick Gold (ABG) 109.60p +2.72%FirstGroup (FGP) 95.20p +2.20%FTSE 250 - FallersBumi (BUMI) 237.00p -8.60%Redrow (RDW) 243.10p -2.64%Evraz (EVR) 101.30p -2.60%Tullett Prebon (TLPR) 359.90p -1.96%Menzies(John) (MNZS) 733.00p -1.81%Countrywide (CWD) 602.50p -1.79%UBM (UBM) 690.50p -1.57%Diploma (DPLM) 608.00p -1.54%Amlin (AML) 409.40p -1.44%Kazakhmys (KAZ) 254.70p -1.39%BC