This Diamond is an oiler's best friend. Diamond Offshore Drilling is a contract offshore oil and gas driller capable of descending in the deep blue to depths of 10,000 feet and deeper. A leading US drilling contractor, Diamond Offshore has 44 offshore drilling rigs, including 32 semisubmersibles, seven jack-up rigs (mobile drilling platforms), and five drillships. Operating in waters off six of the world's continents, Diamond Offshore contracts with almost 50 oil and gas companies; Brazil's PETROBRAS is its major customer. The company, which also provides project management and other drilling-related services, is a subsidiary of Loews Corp.