The diamond baron died on Saturday, Aug. 23, due to complications from a fall, his son, Leon, said, per The New York Times.
Tempelsman was born on Aug. 26, 1929, in Antwerp, Belgium. His family, who were Orthodox Jews, fled Belgium in 1940 as Nazi Germany invaded the country. They came to New York City, and Tempelsman later attended New York University for two years. He then dropped out and worked for his father's new business venture, Leon Tempelsman & Son, which was a diamond merchant company.
Tempelsman would go on to become an internationally influential diamond merchant. By 1950, he had persuaded the U.S. government to buy African industrial diamonds. He convinced the government to stockpile the African industrial diamonds as strategic materials, which were used for national emergencies.
In addition to making millions for his family's company, he would later become the middleman between the African suppliers and the government. Ultimately, working with several African nations, including Ghana and Zaire (now the Democratic Republic of Congo).
His close ties with the government also came to fruition as he was a supporter of the Democratic Party. Beginning in the 1950s, he became a major donor for the party. He would later befriend the staff of several presidents, including John F. Kennedy's speechwriter Ted Sorensen and President Bill Clinton's Secretary of State Madeleine K. Albright and his national security adviser Anthony Lake.
By the 1960 election, Tempelsman set up a meeting with President-elect Kennedy, his wife, and African mining officials. The following year, Tempelsman and his wife, Lilly Burkos, attended a state dinner in 1961, where he and Kennedy Onassis sparked a friendship after speaking briefly to each other in French.
They remained in contact and would write her letters after the president's 1963 assassination and her 1968 wedding to Aristotle Onassis.
Tempelsman and Kennedy Onassis' relationship blossomed decades later, after her second husband, Onassis, died in 1975. By the early 1980s, Tempelsman and Kennedy Onassis made public appearances together. They shared an interest in art, culture, music, the French language (in which they were both fluent) and the finer things in life.
Templesman remained married to Burkos until she died in 2022.
Templesman and Kennedy Onassis were romantically linked until she died in 1994. In 1993, when she was diagnosed with lymphatic cancer, he moved his office into her apartment and escorted her to and from the hospital and in the years leading to her death, he never left her side. He also served as her financial adviser and helped her quadruple the $26 million estate Aristotle left her.
Several years after Kennedy Onassis' death, Templesman had a replica of her diamond-studded band, which she called her "swimming ring," created. Her son, John F. Kennedy Jr., had asked Tempelsman to make a replica of the diamond so he could give it to Carolyn Bessette Kennedy for her wedding ring.
Tempelsman and his estranged wife Lilly had three children: Leon, Marcy and Rena. He is survived by his three children, six grandchildren and seven great-grandchildren.