Rare Kimberley Diamond Now on View
by AMNH on
Beginning today, an extraordinary gem is going on temporary display in the Museum's Morgan Memorial Hall of Gems: the 55.08-carat, champagne-colored Kimberley Diamond.
Cut from a 490-carat crystal, which was found in the 19th century at the Kimberley Mine in South Africa, the Kimberley Diamond was originally cut as a 70-carat gem in 1921. To improve on the gem's proportions and to increase its brilliancy, it was cut to its present emerald cut in 1958.
The Kimberley Diamond exhibit is overseen by George Harlow, curator in the Museum's Department of Earth and Planetary Sciences. Dr. Harlow also curated The Nature of Diamonds, a past Museum exhibition that included much about the origins of diamond—the transparent form of true carbon—and about diamond-mining.
As the exhibition explained, diamonds ascend to the Earth's surface in rare molten rock, or magma, that originates at great depths. Carrying diamonds and other samples from Earth's mantle, this magma rises and erupts in small but violent volcanoes.
Just beneath such volcanoes is a carrot-shaped "pipe" filled with volcanic rock, mantle fragments, and some embedded diamonds. This type of volcanic rock is called kimberlite—after the city of Kimberley, South Africa, where the pipes were first discovered in the 1870s—and where the Kimberley Diamond was mined.
The Kimberley Diamond is on loan from the Bruce F. Stuart Trust.