Petro-Diamond, also known as PDI, is a wholly owned subsidiary of Mitsubishi Corporation. The company was established in 1983 and its principal function is to expand Mitsubishis role in petroleum product trading in the western hemisphere, primarily in the United States. The administrative location, headquartered in Irvine, Calif., is responsible for all products trading from the United States West Coast and Western Canada and operates a modern waterborne terminal facility in Long Beach, Calif. Petro-Diamond s facility located in Irvine employs nearly 30 people.