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Charles the Bold, Duke of Burgundy became the patron of van Bercken and in the 1470s commissioned him to cut a 137 carat (27.4 g) stone that later became known as the Florentine Diamond. Van Bercken experimented with three diamonds belonging to Charles the Bold. One stone was the Beau Sancy, another became the property of Pope Sixtus V, and the third was given by Charles to Louis XI. Later Charles the Bold also sent one of his favorite jewels to be recut, which is now known as the Sancy Diamond.