Nawab Town Police registered a case against unidentified thieves for stealing a diamond necklace worth Rs 500,000 from the exhibition of Indian products at Expo Centre on Sunday. The police said a case had been registered by Nawab Town Police on the complaint of one Kamal Khan late on Sunday night. Sources said on the second day of the exhibition of Indian products at Expo Centre, Johar Town, a woman fainted while visiting a counter of jewellery. The unconscious woman attracted the attentions of administration and the security officials, meanwhile the necklace was stolen. Sources said administration of jewellery stall came to know about the missing set after the closure of the exhibition. Police officials carried out a through search of the visitors and also checked the recordings of CCTV cameras but failed to find any clue. Saddar Division SP Shoaib Khurram Janbaz said investigations were underway and they would arrest the criminals soon.