The two are among a handful of buccaneering businessmen who have made fortunes in countries like Angola, Congo and Guinea, securing positions of influence that have helped their companies profit hugely from the continent's rich natural resources.
The case, brought by the Russian-Israeli Gaydamak over disputed unpaid commissions and dividends against Uzbekistan-born Leviev, also involved testimony on the roles of a Russian rabbi and an Angolan general - and was heard in London.
It was the latest of a rash of cases brought by billionaires from Russia and the former Soviet republics to the courtrooms of the British capital, revealing at times a clash of cultures - and some less than complimentary comments.
Gaydamak, described by the judge as a "volatile and impulsive character" who was "distinctly prone to exaggeration," became involved in Angolan business and politics in the 1990s. He claimed to have suggested to the Angolan government that it obtain control of the country's diamond industry at the height of the civil war so as to cut off the rebels' flow of cash from so-called "blood diamonds." Angola is one of the world's most significant diamond producers and has long been attractive to traders and buyers. Gaydamak also said he was instrumental in setting up the Angolan Diamond Selling Corporation, which had sole buying rights to Angolan diamonds.
He said he had tried to make Leviev a front man for his activities because of a French inquiry into illegal arms supplies. Gaydamak was later cleared of involvement in such supplies. Speaking by video link from Israel because of an outstanding French tax charge, Gaydamak told the High Court on the first day of the trial that he believed he was entitled to about half of Leviev's diamond assets in Angola. His argument rested on his claim that there was a written agreement between them dated December 2001.
Leviev, who has a home in London and who made his name challenging diamond giant De Beers' monopoly on the sale of rough diamonds, denied signing the agreement. Gaydamak argued that Leviev agreed to hold their joint assets, in particular their share in Ascorp and any income from those assets, on trust in equal shares. Leviev's lawyers argued that those claims were settled through a 2011 agreement between the two in which Gaydamak signed away his rights to the assets. Gaydamak said he was induced to sign it.
High Court judge Geoffrey Vos said in his judgment on Friday: "I find that the 2001 agreement was indeed signed by Mr. Gaydamak and Mr. Leviev, and was a valid and enforceable agreement," but he added that the parties had indeed also entered into a valid and binding settlement that took effect in August of last year. He therefore dismissed Gaydamak's claim. Gaydamak later issued a statement in which he said he would apply for permission to appeal.
Leviev did not escape criticism from the judge, who spoke of his arrogance and his "rewriting the history" by leaving some crucial characters out of the story. Vos said he was conscious that he had "not accepted either side's evidence in its entirety."