The Diamantis branch traces its origins to John Constantine Pateras in 1868. His sons Constantine, Nicolas and Diamantis inherited a debt-free freighter, became shareholders in another ship in 1876 and made a joint purchase in 1886. They separated amicably after the First World War. Diamantis and his eldest son John bought a vessel in 1923; in 1937 the family joined the Lemos family in Lemos & Pateras. Costas D. Pateras established Nautilus Shipping in New York in 1948.
After Diamantis died in 1951, his six sons—John, Panagos, Pandelis, Stephanos, Costas and Nicolas—left Lemos & Pateras and began Diamantis Pateras Ltd. on 1 January 1952, becoming shipowners two years later. Nautilus Petroleum Carriers followed in New York in 1958. The group helped found the Oinoussuan Shipping Co-Operation in May 1968. Leandros Shipping’s Piraeus office became the shipping headquarters in 1969, with London acting as exclusive agents. The two Nautilus companies were dissolved during the 1975 oil-trade recession. Later management passed through Leandros and Kyvernitis; Diamantis Pateras Maritime acts as commercial and financial manager.
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