Feature Gems & Gemology, Summer 2008, Volume 44, No. 2

The Use of Laser and X-Ray Scanning to Create a Model of the Historic Koh-I-Noor Diamond

For centuries, the Koh-i-Noor was one of the world’s largest diamonds. It was recut in 1852 from its historic form of 186.1 old carats to an oval of 105.60 modern carats. While the modern shape is well documented, the original form is not. Fortunately, the Natural History Museum in London commissioned a mold of the diamond in 1851 before it was recut. Using one of two plaster replicas made from this mold, the present study captured the surface topology of the original Koh-i-Noor through photography plus laser and X-ray scanning methods. A crystallographic analysis of the major facets determined the diamond’s orientation within a “perfect” diamond crystal, which was used to refute one theory about the diamond’s genealogy. Computer modeling established the orientation of the recut diamond within the historic version. Information from this study was used to create an accurate replica from cubic zirconia.