Oil and gas group Cairn Energy was a high riser after saying that Agora Oil and Gas, a firm it is set to buy, has struck oil at its Skarfjell Prospect in the Norwegian North Sea. Gem Diamonds was also climbing higher after saying that the amount of diamonds recovered at its biggest mine, Letseng, rose 5.9% in the first quarter, while the quality or "grade" of production was over 10% better than the equivalent period of 2011. However, the value of sales fell.Sports media group Perform Group was among the worst performers after saying that it has agreed a partnership to integrate its livesport.tv platform, a network of online sports channels, into the so-called 'smart' TV product line of South Korean firm LG. FTSE 250 - RisersMoneysupermarket.com Group (MONY) 137.10p +6.53%Spirit Pub Company (SPRT) 55.75p +6.19%Cairn Energy (CNE) 331.30p +3.53%Gem Diamonds Ltd. (DI) (GEMD) 271.90p +3.11%Mondi (MNDI) 564.50p +2.54%AZ Electronic Materials SA (DI) (AZEM) 301.20p +2.34%Interserve (IRV) 283.90p +2.34%Genus (GNS) 1,274.00p +2.25%Dunelm Group (DNLM) 514.50p +2.18%Afren (AFR) 135.40p +2.11%FTSE 250 - FallersAquarius Platinum Ltd. (AQP) 126.60p -6.77%International Personal Finance (IPF) 244.10p -4.20%Essar Energy (ESSR) 149.70p -3.92%Elementis (ELM) 198.50p -3.08%Renishaw (RSW) 1,302.00p -3.05%Euromoney Institutional Investor (ERM) 752.00p -2.91%Exillon Energy (EXI) 123.50p -2.83%Ocado Group (OCDO) 107.90p -2.71%Dixons Retail (DXNS) 16.96p -2.53%Ophir Energy (OPHR) 510.00p -2.49%NR