An insurance dispute involving former Tulsa Mayor Kathy Taylor and a $4 million blue diamond ring that she lost while vacationing in California has landed in federal court. Taylor, currently chief of economic development for Tulsa Mayor G.T. Bynum, is seeking an unspecified amount in excess of $75,000 in a breach-of-contract lawsuit against AIG Property Casualty Co. and an insurance broker. In her lawsuit, Taylor says she lost the ring, a gift from her husband, Bill Lobeck, while vacationing in California around Nov. 4. AIG paid Taylor $4 million in December for the lost ring, but she claims the insurance company won’t fully cover the loss, according to court records filed in connection with the lawsuit.