RAPAPORT... Sotheby's will offer a yellow diamond weighing more than 300 carats at its upcoming New York auction, where it is expected to fetch more than $15 million.The pear-shaped, 303.10-carat, fancy-deep-brownish-yellow stone is one of the largest polished diamonds in the world. It is also the largest flawless or internally flawless diamond ever graded by the Gemological Institute of America (GIA), Sotheby's said Monday. Initially called the Incomparable Diamond, the stone was recut from its original 407-carat shield shape to deepen the color and brighten the hue, and renamed the Golden Canary. As the highlight of the December 7 Magnificent Jewels sale, it will be offered without reserve, with bidding starting at $1, Sotheby's noted.The Golden Canary was first discovered in the early 1980s in a pile of rubble by a young girl playing in the backyard of her uncle's house, Sotheby's noted. Miners from the nearby Miba diamond deposit had considered the stone to be too bulky to be diamond bearing and had discarded it. The girl gave the 890-carat rough to her uncle, who sold it to local diamond dealers. The diamond has since been displayed in multiple museums. "The demand and appetite for [extraordinary colored diamonds] continues to grow," said Quig Bruning, head of jewelry for Sotheby's Americas. "Steeped in history, the Golden Canary is one of the most exquisite diamonds to ever be discovered, not only for its sheer size and intensity in color, but for its stunning beauty that is sure to captivate collectors around the world."Sotheby's will showcase the diamond on a world tour prior to the auction, with stops in cities including Dubai; Taipei, Taiwan; Geneva; and Hong Kong.Image: The 303.10-carat Golden Canary diamond. (Sotheby's)