Logan Sapphire: Difference between revisions

The '''Logan Sapphire''' is a {{convert|422.98|carat|g|adj=on|lk=in}} [[sapphire]] from [[Sri Lanka]]. One of the largest blue [[facet]]ed blue sapphires in the world, it was owned by [[Sir Victor Sassoon]] and then purchased by [[M. Robert Guggenheim]] as a gift for his wife, Rebecca Pollard Guggenheim, who gifteddonated the sapphire to the [[Smithsonian Institution]] in 1960. The sapphire's name is derived from Rebecca's new surname after she later marriedmarrying John A. Logan. AsIt of 2022, the Logan Sapphire ishas onbeen displaydisplayed in the National Gem Collection of the [[National Museum of Natural History]] in Washington, D.C., since 1971. It is a mixed cushion-cut sapphire, approximately the size of a large chicken egg, and set in a silver and gold [[brooch]] surrounded by 20 round [[brilliant (diamond cut)|brilliant]] -cut [[diamond]]s.

The Logan Sapphire weighs {{convert|422.98|carat|g|lk=in}} and is approximately the size of a large chicken egg, measuring {{convert|49.23 x 38.26 x 20.56|mm|in|abbr=on}}.<ref name="feather" /><ref name="unearthed" /> It is a mixed cushion-cut [[sapphire]] (having a rounded rectangular shape) and is blue with slight shades of violet.<ref name="website" /><ref name="dictionary">{{cite book |last=Manutchehr-Danai |first=Mohsen |year=2013 |chapter=Cushion cut |title=Dictionary of Gems and Gemology |publisher=[[Springer Science+Business Media]] |page=80, 120 |isbn=978-3-662-04288-5 |oclc=851374055}}</ref> The cut is designed to highlight its color rather than to improve its [[brilliance (gemstone)|brilliance]].<ref>{{cite book |last=O'Neil |first=Paul |year=1983 |title=Gemstones |url=https://archive.org/details/gemstones00onei/mode/2up |url-access=registration |publisher=[[Time Life]] |page=86 |isbn=978-0-8094-4500-4 |oclc=1033664759}}</ref> In 1997, the [[Gemological Institute of America]] determined that the Logan Sapphire's color was natural and that it had not previously undergone [[heat treatment]], a technique that is sometimes used to enhance the color or mechanical properties of gemstones.<ref name="feather" /><ref>{{cite journal |last1=Domanski |first1=Marian |last2=Webb |first2=John |year=2007 |title=A Review of Heat Treatment Research |journal=Lithic Technology |volume=32 |issue=2 |page=154 |doi=10.1080/01977261.2007.11721052|s2cid=128016597 }}</ref> It [[fluorescence|fluoresces]] reddish-orange when exposed to [[ultraviolet]] radiation.<ref name="feather" /> This phenomemonphenomenon, as well as the slight violet tones, indicates trace amounts of the element [[chromium]] in the sapphire's structure.<ref name="unearthed">{{cite book |last=Post |first=Jeffrey Edward |year=2021 |chapter=Logan Sapphire |title=The Smithsonian National Gem Collection—Unearthed: Surprising Stories Behind the Jewels |publisher=[[Abrams Books]] |isbn=978-1-68335-940-1 |oclc=1242914179}}</ref>

The Logan Sapphire is one of the largest blue [[facet]]ed blue sapphires in the world.<ref name="post" /> [[Rutile]] inclusions, commonly found inside [[Sri Lanka]]n sapphires, are visible inside the gemstone.<ref name="unearthed" /> It is set in a silver and gold [[brooch]] and surrounded by 20 round [[brilliant (diamond cut)|brilliant]] cut [[diamond]]s. In total, the diamonds weigh approximately {{convert|16|carat|g}}.<ref name="website" /> The diamonds were likely taken from an antique bracelet or necklace.<ref name="unearthed" /> A 1958 article in ''[[Ladies' Home Journal]]'' by Rebecca Pollard Guggenheim, its owner at the time, suggests that it was set in the brooch sometime after she had acquired it several years earlier, but further details of its setting are unknown.<ref name="unearthed" />

The sapphire was mined from Sri Lanka.<ref name="hansen">{{cite book |last=Hansen |first=Robin |year=2022 |title=Gemstones: A Concise Reference Guide |publisher=[[Princeton University Press]] |page=81 |isbn=978-0-691-21448-1 |oclc=1261879655}}</ref> It is a "Ceylon sapphire", a nameterm givenderived tofrom Srithe Lankanformer sapphiresname of Sri Lanka,<ref name="website" /><ref name="dictionary" /> and likely originates from [[Ratnapura]], known as the "City of Gems".<ref name="website" /><ref name="hansen" /><ref>{{cite journal |last=Saul |first=John M. |year=2018 |title=Transparent gemstones and the most recent supercontinent cycle |journal=[[International Geology Review]] |volume=60 |issue=7 |page=892 |doi=10.1080/00206814.2017.1354730|bibcode=2018IGRv...60..889S |s2cid=133653573 }}</ref> A New York jeweler who possessed the sapphire claimed that its first owner was a Sri Lankan native who was beheaded for withholding his discovery from his leader,. butHowever, this story is likely fabricated.<ref name="unearthed" /> One of the sapphire's early owners was [[Victor Sassoon|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]].<ref name="feather" /> It was exhibited at the [[1939 New York World's Fair]] in 1939.<ref name="unearthed" /> 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.<ref name="feather">{{cite journal |last=Feather II |first=Russell C. |year=2016 |title=The Royal-Blue Logan Sapphire at the Smithsonian Institution |journal=Rocks & Minerals |volume=91 |issue=1 |page=59 |doi=10.1080/00357529.2016.1099135|bibcode=2016RoMin..91...59F |s2cid=131247266 }}</ref>

In the early 1950s, the American diplomat [[M. Robert Guggenheim]] purchased the sapphire from Sassoon. He giftedgave it to his wife, Rebecca Pollard Guggenheim, as a Christmas and anniversary present in 1952.<ref name="feather" /> In ''Ladies' Home Journal'', she recalled her reaction upon seeing it: "I was simply overcome. [...] It's simply not a stone you could wear casually. All I could think was, I'll never be able to wear it. And of course, I loved it." She often wore it on a clip at formal events, but the sapphire was so heavy that she had to wear it with a shoulder strap. In December 1960, a year after Robert's death, Rebecca deeded four-sevenths of it to the Smithsonian Institution, and the remaining portion the following year.<ref name="unearthed" /> This transaction was only in deed; the sapphire was not physically divided, and it was not publicly exhibited until almost a decade later.<ref name="unearthed" /><ref name="white">{{cite journal |last=White |first=John Sampson |year=1986 |title=The Nation's Gem Collection – One Hundred Years |journal=Earth Sciences History |volume=5 |issue=2 |page=167 |doi=10.17704/eshi.5.2.u17x334607410321 |jstor=24138665|bibcode=1986ESHis...5..159W }}</ref> She wanted it to be reserved to be worn only by the [[First Lady of the United States]] "at such state and other occasions as may be appropriate", though it has never been used for this purpose.<ref name="unearthed" />

AsSince of 20221971, the Logan Sapphire ishas been on display in the National Gem Collection of the [[National Museum of Natural History]] in Washington, D.C. (catalog number NMNH G3703-00).<ref name="website">{{cite web |title=Logan Sapphire |url=https://geogallery.si.edu/10002687/logan-sapphire |publisher=[[National Museum of Natural History]] |access-date=March 27, 2022 |archive-url=https://web.archive.org/web/20210528090626/https://geogallery.si.edu/10002687/logan-sapphire |archive-date=May 28, 2021 |url-status=dead}}</ref> It is the largest and heaviest mounted gem in the collection.<ref name="feather" /><ref name="website" />

[[Category:JewelleryJewelry in the collection of the Smithsonian Institution]]