In 1905, Lemoine contacted Sir Julius Wernher, British banker and one of the governors of De Beers Diamond Mines.
Lemoine invited his guests in and left the room; moments later he reappeared naked, to prove that he was not concealing any diamonds in his clothing.
He mixed a number of substances including iron filings and coal into a small crucible, showed the mixture to his guests, and placed it into a furnace in the center of the room.
Lemoine promised to build a factory to duplicate diamonds; actually he just took a picture of an electric plant in southern France and sent it to Sir Julius.
"The Lemoine Affair" is a collection of literary pastiches by Marcel Proust, in which he spoofs the writing styles of several fellow French authors.