Diamond miners are sparkling after two companies in the sector said they had received expressions of interest.Kopane Diamonds, which mines for the gemstones in Lesotho and is up 11%, has entered into an exclusivity agreement with a potential investor in its Liqhobong mine. The potential investor has the potential to take the mine to full production, Kopane said.Diamondcorp, which is developing projects to mine the gemstone in South Africa and Botswana, is up 8% after it, said it is in discussions that may or may not lead to an offer being made for the company.Defence stocks are on the attack after military decoy specialist Chemring, which leads the sector higher, said it will supply the US Department of Defense with a range of decoy flares in a five-year deal worth up to $804m (£502m).Top performing sectors so far todayIndustrial Metals 4,187.09 +1.35%Mining 16,703.14 +1.05%Forestry & Paper 3,339.12 +0.62%Aerospace and Defence 2,825.43 +0.57%Banks 5,007.24 +0.54%Bottom performing sectors so far todaySoftware & Computer Services 550.03 -1.18%Oil & Gas Producers 7,428.80 -0.95%Health Care Equipment & Services 3,054.49 -0.86%Industrial Transportation 1,916.65 -0.76%Pharmaceuticals & Biotechnology 8,228.29 -0.74%