You can’t put a price on beauty; you can put a price on a name. When the National Gallery in London exhibited a painting of Christ in 2011 as a heretofore lost work by Leonardo da Vinci, the surprise in art historical circles was exceeded only by the salivating of dealers and auctioneers. The painting, “Salvator Mundi,” is the only Leonardo in private hands, and was brought to market by the family trust of Dmitry E. Rybolovlev, the Russian billionaire entangled in an epic multinational lawsuit with his former dealer, Yves Bouvier. On Wednesday night, at Christie’s postwar and contemporary...