A possible genius, a smidgen of madness, a twist of science, and an invention that very nearly changed the world—all collide in a giddy, unbelievably true mystery set in turn-of-the-century Paris.

In 1905, inventor Henri Lemoine claimed that he’d uncovered the secret to a coveted alchemy: creating diamonds in a laboratory. It intrigued a host of investors, and it soon made Lemoine an international celebrity. Then he disappeared.

The Diamond Formula is part of Inventions: Untold Stories of the Beautiful Era, a collection of incredible true stories from the belle epoque, an age of innovation, daring, bluster, and beauty when anything seemed possible.