Bismarck Sapphire

The Bismarck Sapphire is a 98.56 carat table-cut sapphire mined in Burma, now Myanmar, and prized for its deep blue color. It is the centerpiece of the Bismarck Sapphire Necklace, a platinum chain set with round brilliant cut diamonds. The central stone is surrounded by baguette-cut diamonds and eight smaller square-cut sapphires placed symmetrically around the edges. The necklace is displayed in the Janet Annenberg Hooker Hall of Geology, Gems, and Minerals at the Smithsonian's National Museum of Natural History in Washington, D.C.

The sapphire was purchased in Sri Lanka in 1926 by Mona Williams, later Countess Mona von Bismarck, during her honeymoon with Harrison Williams, whom she had married on July 2 of that year. The couple traveled on his yacht Warrior, then described as the largest and most expensive pleasure boat in the world. Cartier, Inc. designed the necklace setting in 1935, and the piece was reworked into its current form in 1959.

Mona von Bismarck donated the necklace to the Smithsonian Institution in 1967, among several pieces of jewelry she gave to the museum. It has been displayed near two other famous sapphires in the collection, the Logan Sapphire and the Hall Sapphire and Diamond Necklace.