EOSC 118

EOSC 118 - The Mogul Emerald itself is a single emerald...

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The Mogul Emerald itself is a single emerald from Colombia that is inscribed with Islamic text. This is a famous gem, and I would suggest that you know about it. The 'mogul emeralds' term refers to a set of emeralds with similar properties to the Old World Egyptian emeralds, not to the "Mogul Emerald" itself. The reason for the use of the term 'mogul' is due to the fact that emeralds were favored by the Mogul rulers in India, where the 'mogul emeralds' were mined, and where the Mogul Emerald was carved. The textbook discusses this briefly on page 292. Koh-I-Noor: The Koh-I-Noor diamond (which translates to "Mountain of Light") is the centerpiece of the collection and sits within the Queen Mother's Crown. It originated in the Indian mines in 1304. It came to the British when they annexed Punjab in 1849. The poorly cut 191 carat stone was recut in 1852 to an oval brilliant, weighing 109 carats. It is on display in Tower of London. The current weight of the stone is 105.6 carats, significantly less than the original ~186 carats. The original stone was not cut in a fashion that brought maximum colour and fire to the stone and Queen Victoria had it recut so as to be more of a magnificent gem. In the 38-day recutting process nearly 90 carats were lost in exchange for a more brilliant stone. 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. Gemologically, the Koh-i-Noor is a D-color type IIa stone (Blair et al., 1998). Unlike similar classic "Golconda diamonds" that show pinkish orange fluorescence (Fritsch, 1998), the Kob-i-Noor is inert to long-wave UV radiation but shows a weak green reaction to short- wave UV. Although it has not been given a clarity grade, it shows several feathers/gletzes and a black inclusion under its table (Blair et al., 1998). Hope Diamond: Another famous diamond is the Hope Diamond. It measures 1inch (25.6mm) long by 4/5inch (21.8mm) wide. An asymmetrical cushion antique brilliant cut, it is a fancy diamond with 58 facets plus 2 extra facets on the pavilion and additional facets on the girdle. It was probably discovered at the Kollur Mine in Golconda area of India. This stone is most remarkable because of its deep
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EOSC 118 - The Mogul Emerald itself is a single emerald...

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