The Logan Sapphire is a 422.98-carat (84.596 g) sapphire from Sri Lanka. The mixed cushion-cut stone was owned by Sir Victor Sassoon and then purchased by M. Robert Guggenheim as a gift for his wife, Rebecca Pollard Guggenheim. She later gifted the sapphire to the Smithsonian Institution in 1960; its name is derived from her new surname after remarrying to John A. Logan. As of 2022, the Logan Sapphire is on display in the National Gem Collection of the National Museum of Natural History in Washington, D.C.
Description
The Logan Sapphire weighs 422.98 carats (84.596 g) and is approximately the size of a chicken egg.[1][2] It is a mixed cushion-cut sapphire (having a rounded rectangular shape) and is blue with slight shades of violet.[3][4] The cut is designed to highlight its color rather than its brilliance.[5] In June 1997, the Gemological Institute of America determined that the sapphire had not undergone heat treatment (which is sometimes used to the color or mechanical properties of gemstones) and that its color was natural.[1][6] It fluoresces red-orange when exposed to ultraviolet radiation.[1]
The sapphire is set in a silver and gold brooch and surrounded by 20 round brilliant cut diamonds weighing, in total, approximately 16 carats (3.2 g).[3] It is one of the largest faceted blue sapphires in the world.[2]
History
The sapphire was mined from Sri Lanka.[7] It likely originates from Ratnapura, the "City of Gems".[7][8] One of its early owners was Sir Victor Sassoon, 3rd Baronet of Bombay, a member of the wealthy Sassoon family. According to the Smithsonian Institution, the Sassoons may have acquired the sapphire from an Indian maharaja. Sassoon planned to auction the sapphire in 1941 to raise money for the British war effort during World War II, but the auction did not take place.[1]
In the early 1950s, the American diplomat M. Robert Guggenheim purchased the sapphire from Sassoon as a Christmas and anniversary present for his wife, Rebecca Pollard Guggenheim.[1] She deeded half of it to the Smithsonian Institution in December 1960, a year after Robert's death, and the remaining half the following year.[1][9][10] The transaction was only in deed; the sapphire was not physically divided.[10] Rebecca Guggenheim changed her surname to Logan in 1962 after remarrying to John A. Logan, a management consultant, and the sapphire became known as the "Logan Sapphire".[1][9] It was one of several gifts from wealthy donors that came after the Smithsonian's acquisition of the Hope Diamond in 1958; another was the Napoleon Diamond Necklace.[2] The Logan Sapphire and its ownership was transferred to the Smithsonian in April 1971.[1][10]
As of 2022, the Logan Sapphire is on display in the National Gem Collection of the National Museum of Natural History in Washington, D.C. (catalog number NMNH G3703-00).[3] It is the largest and heaviest mounted gem in the collection.[1][3]
References
- ^ a b c d e f g h i Feather II, Russell C. (2016). "The Royal-Blue Logan Sapphire at the Smithsonian Institution". Rocks & Minerals. 91 (1): 59. doi:10.1080/00357529.2016.1099135.
- ^ a b c Post, Jeffrey E. (1997). The National Gem Collection. National Museum of Natural History. pp. 18, 59. ISBN 978-0-8109-3690-4. OCLC 1036788878.
- ^ a b c d "Logan Sapphire". National Museum of Natural History. Archived from the original on May 28, 2021. Retrieved March 27, 2022.
- ^ Manutchehr-Danai, Mohsen (2013). "Cushion cut". Dictionary of Gems and Gemology. Springer Science+Business Media. p. 120. ISBN 978-3-662-04288-5. OCLC 851374055.
- ^ O'Neil, Paul (1983). Gemstones. Time Life. p. 86. ISBN 978-0-8094-4500-4. OCLC 1033664759.
- ^ Domanski, Marian; Webb, John (2007). "A Review of Heat Treatment Research". Lithic Technology. 32 (2): 154. doi:10.1080/01977261.2007.11721052.
- ^ a b Hansen, Robin (2022). Gemstones: A Concise Reference Guide. Princeton University Press. p. 81. ISBN 978-0-691-21448-1. OCLC 1261879655.
- ^ Saul, John M. (2018). "Transparent gemstones and the most recent supercontinent cycle". International Geology Review. 60 (7): 892. doi:10.1080/00206814.2017.1354730.
- ^ a b "Rebecca P. Logan, 90, Art Patron and Hostess". The New York Times. March 16, 1994. Archived from the original on March 5, 2016. Retrieved March 27, 2022.
- ^ a b c White, John Sampson (1986). "The Nation's Gem Collection – One Hundred Years". Earth Sciences History. 5 (2): 167. JSTOR 24138665.