In February, Swiss art dealer Yves Bouvier thought he was meeting his top cient, Russian billionaire Dmitry Rybolovlev, to work out the final payment for Mark Rothko’s No. 6 (Violet, Green and Red). Considered to be among the finest works in the abstract expressionist's oeuvre, the Rothko was to be sold to the Russian for €140 million ($186 million). Bouvier was instead surprised by the Monaco police who arrested him on charges of fraud.

Rybolovlev alleged that Bouvier had been massively overcharging him for artworks. He was tricked into overpaying by tens of millions of dollars for some works, including a Modigliani nude, claimed Rybolovlev.

Bloomberg dishes the details of the dispute which pits one of Russia's richest men against his trusted art dealer, and exposes the shady side of private art sales.