Set aside the elixir stories and a documentable man remains, visible in three archives. The first is diplomatic. In 1760, during the Seven Years War, Saint Germain appeared at The Hague conducting unofficial peace soundings with English contacts on behalf, he said, of Louis XV's private diplomacy; the foreign minister Choiseul, outside the secret and furious at the intrusion, demanded his arrest, and the count fled to England. The affair is preserved in the correspondence of the ministers and ambassadors concerned, and it fits what is known of the king's parallel foreign policy, whether or not the count's commission was real. The second is musical.
Under the name Saint Germain he published genuine compositions in London, songs and instrumental pieces issued by established printers in the 1740s, with further pieces later; the music survives and is occasionally performed, competent gallant writing that proves at least one of his accomplishments was exactly as advertised. The third is industrial. His last years were spent at Eckernfoerde in Schleswig under the protection of Prince Charles of Hesse-Kassel, working on dye processes and other chemical schemes the prince funded and partly recorded; the parish register there notes his burial in February 1784. Diplomat without portfolio, published composer, projector of dyes: the verifiable career is odder, in its way, than the legend, because it required real abilities the legend never needed.