Great Mogul Diamond

Great Mogul is believed to have been discovered around 1650 most probably around Kollur Mine in the Golconda region of southern India. Tavernier described the diamond as "The stone is of the same form as if one cut an egg through the middle".
History.
The rough diamond was gifted by Emir Jemla to Shah Jahan, the 5th Mughal emperor, as part of diplomacy between the two families.
Jemla described it as "that celebrated diamond which has been generally deemed unparalleled in size and beauty."
A Venetian lapidary named Ortensio Borgio was assigned to cut the stone. It is believed that the Great Mogul Diamond exhibited several inclusions. Rejecting the idea of cutting the diamond into several fine stones, Borgio decided to address the inclusion problem by grinding away at it until the unwanted flaws were gone. Much to the horror of the Emperor, Borgio’s work yielded very poor results, including a great loss of weight. Shah Jehan spared Borgio’s head, instead fining him 10,000 rupees (all the money he had) for his ineptitude. Originally this story was believed to refer to the Koh-i-Noor Diamond, however recent research appears rather it was this stone.
Around 1665 the Shah’s son, Aurangzeb, showed the stone to the famous jeweler and world traveler Jean Baptiste Tavernier. At that time Tavernier wrote in his Six Voyages: "The first piece that Akel Khan (Chief Keeper of the King's jewels) placed in my hands was the great diamond, which is rose cut, round and very high on one side. On the lower edge there is a slight crack, and a little flaw in it. Its water is fine, and weighs 319-1/2 ratis, which makes 280 of our carats, the rati being ⅞th of a carat."
Later, the Great Mogul Diamond was transferred to Lahore Subah and became part of the spoils of war when Mughal India was invaded and Lahore and then Delhi sacked by the Persian ruler Nadir Shah. Nadir Shah returned with the stone to his home in Isfahan in 1739 from the Nawabs of Punjab. However, Nadir Shah’s ownership proved shorted-lived. He was assassinated in 1747 and the stone disappeared. 
Most modern scholars are now convinced that the Great Mogul is actually the Orlov Diamond, today part of Catherine the Great's imperial Russian sceptre in the Kremlin.
See also.
Anna Malecka, The Great Mughal and the Orlov: One and the Same Diamond? The Journal of Gemmology, vol. 35, no. 1, pp. 56–63 ;
https://search.proquest.com/openview/9d9af4a10dc0f510b7c28430d78baa37/1?pq-origsite=gscholar&cbl=2041200