What is modernity, if not a dogged persistence to separate human artifice from non-human nature? This distinction permeates our lives, and indeed underlies the geological epoch, the human-modified "Anthropocene," in which we currently live. Yet to speak in universal terms of "human" activities or "human" epochs can obscure as well as illuminate. This project examines the history of a practice, the surgical modification of living pearl-bearing shellfish, chat redefined the limits of nature and artifice in different parts of the twentieth century world. It follows the global activities of Mikimoco Kokichi, a man whose pearl cultivation estates grew out of changes in imperial Japanese fisheries and patent law. Mikimoto's capitalism depended upon the ownership of living creatures, their habitats, and their productive capabilities. His "Japanese" pearls provoked coordinated resistance from European gem wholesalers who, by the 1930s, engineered the recategorization of the new "cultured" pearls apart from ocher "natural" ones.